“Your association has taken a significant role in fostering public awareness of nuclear disarmament and has led to its advancement.”
– Kazi Matsui
Mayor of Hiroshima
June 2, 2022
Arms Control Today

Biden Issues Executive Order on AI Safety

December 2023
By Michael T. Klare

Responding to growing public anxiety over the potential dangers posed by the expanding use of artificial intelligence (AI), President Joe Biden issued an executive order on Oct. 30 intended to ensure the “safe, secure, and trustworthy” application of the powerful technology.

With Vice President Kamala Harris (R) looking on, U.S. President Joe Biden signs an executive order on advancing the safe, secure, and trustworthy development and use of artificial intelligence at the White House on October 30.  (Photo by Brendan Smialowski/AFP via Getty Images)The order followed the public release of ChatGPT and other generative AI programs that are able to create text, images, and computer code comparable to that produced by humans. On occasion, these programs have suffused those materials with false and fabricated content, provoking widespread unease about their safety and reliability.

Other AI-enabled products used to identify possible criminal suspects also have been shown to produce inaccurate outcomes, raising concerns about racial and gender biases introduced when the systems were being “trained” by computer technicians.

To overcome such anxieties, the executive order mandates a wide variety of measures intended to bolster governmental oversight of the computer technology industry and to better protect workers, consumers, and minority groups against the misuse of AI. Most of these apply to domestic industries and institutions, but some have a significant bearing on national security and arms control.

One of the order’s most consequential measures is a requirement that major tech firms such as Google, Microsoft, and OpenAI notify the federal government when developing any “foundational model”—a complex AI program such as the one powering ChatGPT—“that poses a serious risk to national security, national economic security, or national public health.” They must also share the results of all “red team” tests, programs designed to probe newly developed AI products and identify any hidden flaws or weaknesses, conducted by those firms.

Although the Oct. 30 order does not empower the government to block the commercialization of programs found to be deeply flawed in these tests, it might deter major institutional clients, including the U.S. Defense Department, from procuring such products, thereby prompting industry to place greater emphasis on safety and reliability.

Along similar lines, the order calls on the National Institute of Standards and Technology to establish rigorous standards for red-team testing of major AI programs before their release to the public. Compliance is not obligatory, but such standards are likely to be widely adopted within the industry. The same standards also will be applied by the departments of Energy and Homeland Security in overcoming potential AI system contributions to “chemical, biological, radiological, nuclear, and cybersecurity risks.”

More closely related to national security and arms control is a measure intended to prevent the use of AI in engineering dangerous biological materials, a significant concern for those who fear the utilization of AI in the production of new, more potent biological weapons. Under the Biden order, strong new standards will be established for biological synthesis screening, and any agency that conducts life science research will have to abide by them as a condition of future federal funding.

Several other key provisions bear on national security in one way or another, but in recognition of the issue’s complexity, the order defers full consideration of AI’s impact on these issues to a separate national security memorandum to be developed by the White House National Security Council staff in the coming months. Once completed, this document will dictate how the U.S. military and intelligence communities “use AI safely, ethically, and effectively in their missions.”

The President acted to ensure the “safe, secure, and trustworthy” application of artificial intelligence in response to growing public anxiety over AI’s potential dangers.

Israeli Arrow System Downs First Missiles in Combat

December 2023
By Mohammadreza Giveh

Israel used its Arrow-3 missile defense system to shoot down a ballistic missile, marking the system’s first combat interception. The ballistic missile was launched at Israel from the direction of the Red Sea on Nov. 9, presumably by Houthi militants in Yemen.

A version of the Arrow-3 missile defense system that Israel on November 9 used to shoot down a ballistic missile, marking the system’s first combat interception.  (Photo by Sven Nackstrand/AFP via Getty Images)Produced by Israel Aerospace Industries in collaboration with the U.S. Missile Defense Agency, the surface-to-surface Arrow missile defense system, considered the top tier of Israel’s multilayered air defenses, is focused on incoming ballistic missiles and consists of the Arrow-2 and the Arrow-3 variants.

The more advanced Arrow-3 is intended to defend against longer-range missile threats and the Arrow-2 to defend against regional short-range or medium-range threats. The Arrow-2 system had its first successful intercept on Oct. 31.

The Nov. 9 interception came as Israel and Hamas militants were waging war in Gaza. It was the Arrow-3’s “first operational interception since its operational deployment in 2017…[and] follows the recent success of the first operational interception” by the Arrow-2 the prior week, according to a joint statement by the Israeli Defense Ministry and the Israel Defense Forces (IDF).

Breaking Defense quoted the IDF as saying the missile on Nov. 9 came from the Red Sea region, presumably meaning that Houthi militants launched that attack.

The Arrow-2 interception happened outside the atmosphere at an altitude of approximately 60 miles, making it the first instance of space combat, The Jerusalem Post reported.

“Our armed forces launched a large batch of ballistic and winged missiles and a large number of drones at various targets of the Israeli enemy,” a Houthi spokesperson said in claiming responsibility for the Oct. 31 attacks, according to CNN.

Israel used its Arrow-3 missile defense system to shoot down a ballistic missile.

Why We Must Reject Calls for a U.S. Nuclear Buildup

November 2023
By Daryl G. Kimball

The experience of the Cold War teaches us that an unconstrained arms race has no winners, only losers. Leaders in Beijing, Moscow, and Washington need to engage in nuclear risk reduction talks, negotiate sensible and verifiable reductions of their arsenals, and refrain from building new destabilizing types of weapons rather than proceed down the dangerous path of unconstrained nuclear competition.

The Congressional Commission on the Strategic Posture of the United States presents its report on Oct. 12. (Arms Control Association photo)Regrettably, the final report of the Congressional Commission on the Strategic Posture of the United States, released in October, suggests that, in response to Russia’s nuclear and military behavior and the anticipated growth of China’s nuclear arsenal, the U.S. arsenal “should be supplemented” to add more capability and flexibility to counter two “near-peer” nuclear adversaries. The bipartisan commission, which consists of 12 national security insiders, also advises that the United States “must be ready to deter and defeat” both adversaries in simultaneous wars, enhance its missile defense capabilities, and significantly bolster its nuclear weapons capabilities, including with new theater-range weapons.

If there is a military conflict between nuclear-armed states, however, deterrence will have failed, and there will be no “winners.” Once nuclear weapons are used in a war between nuclear-armed adversaries, there is no guarantee that a nuclear war could be contained.

In the current context, any decision to increase the number of deployed U.S. strategic nuclear weapons higher than the levels of the New Strategic Arms Reduction Treaty (New START) could trigger a dangerous action-reaction cycle. It would not enhance deterrence in the face of China’s growing nuclear capabilities or Russia’s existing capabilities. In response, China could deploy more nuclear weapons on an even wider array of delivery systems, and Russia would seek to match any increases in the U.S. nuclear force.

As U.S. Defense Secretary Lloyd Austin noted on Dec. 9, 2022, “Nuclear deterrence isn’t just a numbers game. In fact, that sort of thinking can spur a dangerous arms race.”

The U.S. nuclear arsenal, which includes roughly 1,800 deliverable strategic warheads, 150 substrategic warheads, and thousands of warheads in reserve, still exceeds what is necessary to hold a sufficient number of adversary targets at risk so as to deter a nuclear attack.

U.S. National Security Advisor Jake Sullivan, in an address on June 2, reiterated that “the United States does not need to increase our nuclear forces to outnumber the combined total of our competitors to effectively deter them.”

Increasing the number of nuclear weapons or adding new types of nuclear weapons to the U.S. arsenal would also be prohibitively expensive. A Congressional Budget Office report in July estimated that the existing U.S. nuclear modernization program would cost a staggering $756 billion in 2023-2032. The commission’s recommendations, if pursued, would require hundreds of billions of dollars more.

Although the commission’s report generally supports U.S. efforts to engage China and Russia in nuclear risk reduction, it seriously underplays the importance of strong U.S. leadership on arms control in preventing an unconstrained nuclear arms race. Its recommendations in this area reflect a failure of imagination, a lack of consensus, or both.

Contrary to existing U.S. policy and practice, “the [c]ommission recommends that once a strategy and its related force requirements are established, the U.S. government determine whether and how nuclear arms control limits continue to enhance U.S. security.” In reality, arms control is a critical element of such an effective national security strategy, not an afterthought. That is why the Biden administration’s 2022 Nuclear Posture Review states that “[m]utual, verifiable nuclear arms control offers the most effective, durable and responsible path to reduce the role of nuclear weapons in our strategy and prevent their use.”

According to Sullivan, the United States is ready to engage in nuclear arms control diplomacy with Russia and other nuclear-armed members of the nuclear Nonproliferation Treaty (NPT) “without preconditions.” He emphasized that “rather than waiting to resolve all of our bilateral differences, the United States is ready to engage Russia now to manage nuclear risks and develop a post-2026 arms control framework.”

New bilateral nuclear arms control limits with Russia may be difficult to achieve as long as Russia’s war on Ukraine rages. Even so, the United States could seek an executive agreement or a reciprocal unilateral arrangement verified with national technical means of intelligence that commits Russia and the United States to respect New START’s central limits on strategic arsenals until a more permanent, comprehensive nuclear arms control arrangement is concluded.

Instead of threatening to take actions that might accelerate dangerous nuclear competition, the United States must exercise prudent nuclear restraint and energetically pursue effective arms control and disarmament diplomacy with Russia, China, and other nuclear-armed states inside and outside of the NPT.

The experience of the Cold War teaches us that an unconstrained arms race has no winners, only losers. Leaders in Beijing, Moscow, and Washington need to engage in nuclear risk reduction talks, negotiate sensible and verifiable reductions of their arsenals, and refrain from building new destabilizing types of weapons rather than proceed down the dangerous path of unconstrained nuclear competition.

A New Argument for Nuclear Arms Control: Climate Change

November 2023
By Kenneth C. Brill

There is no shortage of reasons to be pessimistic about the future of nuclear arms control.

Smoke and flames rise from a mountain during a wildfire in Chongqing, China in 2022. Every nuclear- and non-nuclear-weapon state will confront the impacts of climate change in the years to come. (Photo by VCG/VCG via Getty Images)Relations among the major nuclear powers have soured. Russian President Vladimir Putin has made veiled nuclear threats related to Russia’s full-scale war on Ukraine and stopped Russia’s implementation of the New Strategic Arms Reduction Treaty. China plans to increase its nuclear weapons stockpile and has rejected U.S. efforts to engage on strategic nuclear issues.1 In the United States, a rising chorus argues that nuclear arms control is over and that the U.S. nuclear stockpile should be increased, not just modernized.2 Meanwhile, states such as India, North Korea, and Pakistan are increasing their nuclear stockpiles.3

Nonetheless, another increasingly evident global threat provides compelling reasons for nuclear-armed nations to assess that a renewed push for nuclear arms control is very much in their long-term security interests. That threat is the impact of climate change on the natural world. The increasing number, intensity, and variety of natural disasters across the globe in recent years have demonstrated the growing danger to all states, whether nuclear armed or not. The cascading impacts of climate change on the natural world are no longer simply a concern of environmentalists or insurance companies; they are becoming a national and global security challenge that will intensify for decades to come. Dealing with this new threat to prosperity and stability will require developing an international strategic balance that recognizes that weapons of war are not the best defense against what will be the most sustained threats of the 21st century and beyond.

Reviving arms control diplomacy will be essential to achieving this new strategic balance. The goals of that diplomacy would be to rebuild or, in some cases, establish confidence among nuclear-armed states; reinforce constructive existing nuclear norms; sharply reduce the number of nuclear weapons; and free up resources to deal with the national and global consequences of climate change.

Facing a Common Threat

Nuclear arms control diplomacy was invented at the height of the Cold War when distrust between nuclear powers was deep, communications limited, and the threat of conflict a daily reality. Every U.S. president from Dwight Eisenhower until Donald Trump undertook diplomatic initiatives that produced arms control agreements. As a result, the combined U.S. and Russian stockpiles were reduced from some 60,000 weapons in the mid-1980s to a little more than 12,000 in 2020.4 In addition, constructive new norms—no use of nuclear weapons on the battlefield and no nuclear weapons testing—were established and are still holding.5

Despite the contentious post-cold war geopolitical situation, arms control diplomacy succeeded because the parties involved had shared interests. That perception of shared interest seems elusive now, given stepped up Chinese-U.S. competition over shaping the international order, Putin’s break with the West, and India’s ongoing strains with Pakistan and China. Even so, every nuclear- and non-nuclear-weapon state faces a common threat in the coming decades and beyond, namely the cascading impacts of climate change on the natural world within and outside their borders. That common threat is an opportunity for developing common ground on arms control.

Money for Nothing…or for Something?

Nuclear weapons are expensive to build, maintain, and modernize. According to one estimate, in 2021 the world’s nine nuclear-weapon states spent $82.4 billion on their nuclear weapons programs, with the United States investing the most, followed by China and Russia.6 The estimated cost for the U.S. nuclear stockpile modernization program over its planned 30-year life span is $1.5 trillion.7

In January 2022, China, France, Russia, the United Kingdom, and the United States issued a statement reiterating what U.S. President Ronald Reagan and Soviet leader Mikhail Gorbachev vowed in 1985, that a nuclear war can never be won and must never be fought. They also committed to the ultimate goal of a world without nuclear weapons with undiminished security for all.8 Assuming that those commitments are serious, vast sums of money are being spent on weapons that none of the nuclear-weapon states expects to use, even as they insist that possessing nuclear weapons is necessary in today’s geopolitical environment. Climate change, however, will upset the notion of what constitutes the most pressing national threats.

High temperatures, droughts, and intense rain events that produce inland flooding of arable land will reduce food production and increase food prices. Rising sea levels, more intense storms, and associated flooding will destroy coastal infrastructure, undermining the capacity of coastal cities to support their populations. Cities and infrastructure in many countries also will be affected by intense storms that result in inland flooding. High temperatures and droughts will reduce the national GDP of many states and make some areas unable to support current populations.9

The World Bank reports that these factors could force some 216 million people to be displaced within their own countries by 2050, with internal displacement “hotspots” occurring as early as 2030.10 A European think tank foresees an even more dire situation, estimating that some 1 billion people could be displaced by 2050 due to climate change, conflict, and civil unrest. Some, possibly many, of those internally displaced people subsequently will seek to migrate to other countries.11 A White House study assessed that climate-related migration has potentially significant negative implications for international security, instability, conflict, and geopolitics.12

Dealing with climate change will be expensive. A 2018 report assessed the then net present value of projected damages globally by 2100 from an increase in global temperatures of 1.5 degrees Celsius at $54 trillion or $69 trillion from an increase of 2.0 degrees.13 Meanwhile, Swiss Re, a leading global reinsurer, estimates that if greenhouse gas emissions are not reduced quickly, climate change is likely to cut total global economic output by some 11-14 percent, or up to $23 trillion.14 The International Energy Agency estimates it will cost $5 trillion in annual new energy investments by 2030 to meet the Paris Agreement goal of holding the increase in global temperatures to 1.5 degrees Celsius.15 The UN Environment Programme estimates that climate change adaptation costs faced by developing countries alone will be $140-300 billion annually by 2030 and $280-500 billion by 2050.

Climate change will not just hurt developing countries; nuclear-weapon states also will feel the pain. For example, Swiss Re assesses that China’s economy has the highest climate risk of any major economy, noting that its GDP could be reduced by as much as 6.6 percent by 2048 even if global temperatures increase only 1.5 degrees Celsius or by 18 percent if they rise by 2.6 degrees Celsius.16 The World Bank agrees, noting the vulnerability of China’s coastal cities, such as Shanghai and Guangzhou, to rising sea levels and its agricultural regions to drought.17 Among other nuclear-armed states, the U.S. intelligence community assesses India, North Korea, and Pakistan to be highly vulnerable to the cascading impacts of climate change.18

Climate change has economic and financial effects on the United States as well. Weather and climate disasters from 2016 to 2022 cost the country more than $1 trillion in storm and related damages, and 2023 already has set a record for the number of U.S. natural disasters producing more than $1 billion in costs.19 More broadly, a 2018 study estimated that U.S. GDP could be cut 10 percent by 2100 with a business-as-usual approach to climate change.20 Meanwhile, the White House reports that a failure to act on climate change could reduce revenue to the U.S. Department of the Treasury by $2 trillion per year, even as demands for climate-related expenditures, such as disaster relief and crop insurance payments, increase.21

Developed nations will be under increasing pressure to financially support developing countries in dealing with the effects of climate change. The need in developed countries to reduce transnational climate migration from developing countries will be a major incentive to do so. The growing political, economic, and humanitarian ramifications of climate change-related transnational migration are already evident, for example, along the southern U.S. border, in the flow of migrants across the Mediterranean to Europe, and in the movement of Bangladeshis into India. If not addressed, this climate-related flow of human misery only will increase and become more unsettling in the coming decades.

A Forever Timescale

The fiscal consequences of climate change not only will be substantial for developed and developing nations, they also will be enduring. Emitted carbon dioxide remains in the atmosphere for 300 to 1,000 years.22 Dramatically reducing greenhouse gas emissions and then dealing with the impact of these emissions on the natural world, including by removing them from the atmosphere, will therefore be the work of and fiscal burden on many generations. This means climate change-related expenditures and economic costs will become a substantial factor for most countries essentially in perpetuity.

Geopolitics inevitably will be affected by climate changes. Polar melting will create opportunities for jockeying among polar nations and others over new sea-lanes and some newly exposed territory, but that is more likely to be transitory than world changing. What comprises national power in a time of a transforming natural world, however, is likely to be different than what it was earlier. In today’s geopolitics, nuclear weapons represent power and status. Proponents of nuclear weapons cite their value in deterring attacks from other nations. Yet, nuclear weapons will not deter the growing threats to national stability and power from sea level rise, drought, or rising temperatures that reduce national economic output. They also will not deter the displacement of domestic populations or the stresses produced by transnational migration.

This submarine is part of China’s 094A Jin-class of nuclear sea-based capabilities, which is equipped to carry up to 12 sea-launched ballistic missiles. China, Russia and the United States are all investing heavily in their nuclear weapons arsenals but experts say their national GDPs will decline if the climate change threat is not addressed. (Photo by Mark Schiefelbein/AFP via Getty Images)In the future, power is likely to accrue to states that successfully sustain their economies and national cohesion despite the pressures created by a mutating natural world. This will take considerable, sustained investments in climate change mitigation, adaptation, and resilience. These investments will dwarf what is being done today and will strain national climate-impaired fiscal capacities.

As a result, nuclear weapons increasingly will be neither a status symbol, nor relevant to the most urgent threats facing nuclear- and non-nuclear-weapon countries, but instead become an opportunity cost. That is, money spent on weapons that no one wants or has a plausible reason to use is money that cannot be used to address climate-related threats to national prosperity, stability, and security, which will be tangible and domestically urgent.

Mutually Assured Destruction or a Mutually Assured Future?

Despite fiscal pressures and growing political demands to address climate change-related challenges, particularly at home, no nuclear-armed state will unilaterally reduce its nuclear stockpile. Nuclear arms control diplomacy needs to be revived to help nuclear-armed nations and the global community as a whole transition from mutually assured destruction strategies to a strategic balance that addresses climate change impacts and promotes a mutually assured future.

Arms control diplomacy in a time of climate change must be different from the Cold War variety. Although the nuclear Nonproliferation Treaty and the Chemical Weapons Convention are global agreements, the bulk of the arms control instruments were negotiated on a bilateral basis between the Soviet Union/Russia and the United States. With the current roster of 10 nuclear- or near-nuclear-armed states, the time for bilateral arms control diplomacy is over.

Yet, the unsuccessful U.S. efforts to engage China in nuclear arms discussions and the failed multilateral efforts to persuade North Korea to abandon its nuclear weapons program demonstrate the challenges of moving beyond the Russian-U.S. construct of nuclear negotiations. One of the difficulties is that, despite sizeable reductions in the past, there is still a large gap between the Russian and U.S. nuclear stockpiles and everyone else. Another challenge is the deep distrust and tensions among most of the nuclear- or near-nuclear-armed states.

A Russian Iskander-M dual-capable missile system is launched in 2018. Arms Control Today contributor Kenneth C. Brill writes that nuclear weapons will not deter the growing threats from climate change. (Photo by Mil.ru/Wikimedia Commons)Reviving nuclear arms control and making it relevant for the climate change age will require leadership and creativity; it will also take time. Moscow and Washington took decades to reach significant bilateral nuclear arms control agreements. Negotiations involving even more nations with significantly different weapons programs will be even more complex and time consuming. Nonetheless, climate change impacts are growing; and a status quo approach will become increasingly untenable for nuclear-armed nations and others, so it is time to get started with thinking about how to advance arms control in a time of climate change.

Despite its polarized domestic politics, strains with China and Russia, and recent quiescence on arms control, the United States is best placed to initiate new thinking and action on nuclear arms control. It has experience in developing and moving forward with nuclear-related initiatives, such as President Barack Obama’s nuclear security summits, and it is allied with or has constructive relations with five other nuclear-armed states (France, India, Israel, Pakistan, and the UK).

The first step in the diplomatic process would be for the United States to commit internally to pursuing nuclear arms control talks with other nuclear-weapon powers to reduce the threat of the use of nuclear weapons and allow greater focus on dealing sustainably with the impacts of climate change at home and elsewhere. Such an initiative would take years to develop and produce results, so bipartisan support would be essential, if challenging to obtain. Toward this end, the United States should explore the subject early on with its two NATO nuclear-weapon allies, France and the UK, with the goal of building a unified core to move the process forward procedurally and substantively.

Although negotiations eventually should focus on numbers of weapons, beginning with numbers would be unproductive, given existing tensions among various nuclear-armed states and the differences in their nuclear weapons programs. In his final book, the arms control scholar and practitioner Michael Krepon sensibly suggested that a multilateral arms control negotiation might gain traction by focusing on reinforcing three nuclear norms: no use of nuclear weapons in a conflict, no testing of nuclear weapons, and no proliferation of nuclear weapons to non-nuclear-armed states.23

The initial efforts at developing a multilateral nuclear arms control negotiation should focus on the eight most developed of the 10 nuclear-armed and near-nuclear-armed states, namely China, France, India, Israel, Pakistan, the UK, and the United States. Ideally, after gaining French and UK support, the United States would engage each of the remaining states on their concerns and ideas for advancing a process that would strengthen confidence among the nuclear-armed states and encourage collaboration on ensuring that nuclear weapons materials remain secure, despite the impacts of climate change.

New arms control initiatives will be needed so that funds now directed at nuclear weapons can be invested in projects dealing with the threat of climate change. In August, Joint Forces Training Base in Los Alamitos, Calif. inaugurated a project intended to increase energy resilience for the base and Southern California by adding locally generated carbon-free renewable electricity to the grid.  (Photo by Frederic J. Brown/AFP via Getty Images)If the initial U.S.-led bilateral consultations show promise, a meeting should be convened of the eight states consulted or some sub-group to explore how much further the process could go. Because the perception of U.S. leadership on this issue would be anathema to at least two nuclear-armed states, a neutral convener would be needed to arrange group meetings. The logical choice is the International Atomic Energy Agency, where all eight states are members. It could convene low-key meetings of the group and keep initial discussions informal and out of the limelight until all parties concur that there is something to be gained by this process. As the process proceeds, the states gain confidence with one another, and the impacts of climate change become increasingly evident, participants can expand their ambitions and move toward negotiating reduced numbers of nuclear weapons.

Once there is engagement and positive momentum on making nuclear arms reductions among the eight, which could take years to achieve, it would be useful for some of the eight to reach out to North Korea and possibly to Iran to invite them into the process.

Problems Create Opportunities

Given the state of international affairs, particularly the ongoing violence in Ukraine and the renewed violence in the Middle East, the idea of a nuclear arms control initiative may sound absurd. Yet, a changing climate will alter the natural world dramatically and, in so doing, fundamentally change what counts as national and global security. This transforming world requires a new strategic balance between nuclear-armed nations, as well as between all nations and the natural world. Robust nuclear arms control diplomacy can help establish that new strategic balance between nations, significantly reduce or eliminate nuclear weapons, and free up resources needed to deal with the daunting financial challenges of restoring balance with the natural world.

The road to positive results for this new arms control diplomacy will be long and challenging, requiring unprecedented cooperation and collaboration between nations, as well as between those officials managing security issues and those dealing with climate-related issues. Although arms control diplomacy was useful in the 20th century, it is essential for the 21st century and beyond. It is time to get started on it.



1. Shannon Bugos, “Pentagon Sees Faster Chinese Nuclear Expansion,” Arms Control Today, December 2021, p. 26.

2. Bryant Harris, “U.S. Nuclear Commander Warns of Deterrence ‘Crisis’ Against Russia and China,” Defense News, May 4, 2022; Patty-Jane Geller, “U.S. Nuclear Weapons,” in 2023 Index of U.S. Military Strength, ed. Dakota L. Wood (Washington: The Heritage Foundation, 2023), pp. 481-506, https://www.heritage.org/sites
; Chris Gordon, “U.S. Should Consider Expanding Nuclear Arsenal to Cope With China and Russia, Study Says,” Air and Space Forces Magazine, March 31, 2023, https://www.airandspaceforces.com/us-consider-expanding-nuclear-arsenal-china-russia/.

3. Stockholm International Peace Research Institute, “States Invest in Nuclear Arsenals as Geopolitical Relations Deteriorate—New SIPRI Yearbook Out Now,” June 12, 2023, https://www.sipri.org/media/press-release/2023/states-invest-nuclear-arsenals-geopolitical-relations-deteriorate-new-sipri-yearbook-out-now.

4. “Historical Nuclear Weapons Stockpiles and Nuclear Tests by Country,” Wikipedia, n.d., https://en.wikipedia.org/wiki/Historical_nuclear_weapons_stockpiles_and_nuclear_tests_by_country (accessed October 18, 2023).

5. Michael Krepon, Winning and Losing the Nuclear Peace: The Rise, Demise, and Revival of Arms Control (Stanford, CA: Stanford University Press, 2021), p. 9.

6. Giulia Carbonara, “U.S. Nuclear Weapons Spending Compared to China and Russia,” Newsweek, June 14, 2022, https://www.newsweek.com/us-nuclear-weapons-spending-compared-china-russia-1715542.

7. Kingston Reif, “The Trillion (and a Half) Dollar Triad?” Arms Control Association Issue Brief, Vol. 9, No. 6 (August 18, 2017), https://www.armscontrol.org/issue-briefs/2017-08/trillion-half-dollar-triad.

8. The European Leadership Network, “The Reagan-Gorbachev Statement: Background,” November 17, 2021, https://www.europeanleadershipnetwork.org/commentary/the-reagan-gorbachev-statement-background/; The White House, “Joint Statement of the Leaders of the Five Nuclear-Weapon States on Preventing Nuclear War and Avoiding Arms Races,” January 3, 2022, https://www.whitehouse.gov/briefing-room/statements

9. The Intergovernmental Panel on Climate Change, “Summary for Policymakers,” 2018, https://www.ipcc.ch/site/assets/uploads/sites/2/2022/06/SPM_version_report_LR.pdf.

10. The World Bank, “Climate Change,” May 12, 2023, https://www.worldbank.org/en/topic/climatechange/overview.

11. Institute for Economics & Peace, “Over One Billion People at Threat of Being Displaced by 2050 Due to Environmental Change, Conflict and Civil Unrest,” September 9, 2020, https://www.economicsandpeace.org/wp-content/uploads/2020/09/Ecological-Threat-Register-Press-Release-27.08-FINAL.pdf.

12. The White House, “Report on the Impact of Climate Change on Migration,” October 2021, https://www.whitehouse.gov/wp-content/uploads/2021/10/Report-on-the-Impact-of-Climate-Change-on-Migration.pdf.

13. “Risks Associated With Global Warming of 1.5ºC or 2ºC, Tyndall Briefing Note, May 2018, https://tyndall.ac.uk/wp-content/uploads/2021/11/briefing_note_risks_warren_r1-1.pdf.

14. Christopher Flavelle, “Climate Change Could Cut World Economy by $23 Trillion in 2050, Insurance Giant Warns,” The New York Times, April 22, 2021.

15. International Energy Agency, “Net Zero by 2050: A Roadmap for the Global Energy Sector,” May 2021, https://iea.blob.core.windows.net/assets/7ebafc81-74ed-412b-9c60-5cc32c8396e4/NetZeroby2050-ARoadmapfortheGlobalEnergySector-SummaryforPolicyMakers_CORR.pdf.

16. Swiss Re Institute, “The Economics of Climate Change,” April 22, 2021.

17. The World Bank, “China Country Climate and Development Report,” October 2022, https://www.worldbank.org/en/country/china/publication/china-country-climate-and-development-report; Dharisha Mirando et al., “CWR City Factsheets: At-a-Glance Coastal Threat Assessment for 20 APAC Cities,” November 2020, pp. 9-10, 25-26, https://www.chinawaterrisk.org/wp-content/uploads/2020/11/CWR_APACCT_20_Index_CityFactsheets.pdf.

18. U.S. National Intelligence Council, “National Intelligence Estimate: Climate Change and International Responses Increasing Challenges to US National Security Through 2040,” NIC-NIE-2021-10030-A, n.d., https://www.dni.gov/files/ODNI/documents/assessments/NIE_Climate_Change_and_National_Security.pdf.

19. National Centers for Environmental Information, U.S. National Oceanic and Atmospheric Administration, “Time Series,” October 23, 2023, https://www.ncei.noaa.gov/access/billions/time-series.

20. Caroline McMahan, “The Rising Costs of Global Warming,” Michigan Journal of Economics, March 13, 2021, https://sites.lsa.umich.edu/mje/2021/03/13/the-rising-costs-of-global-warming/.

21. Candace Vahlsing and Danny Yagan, “Quantifying Risks to the Federal Budget From Climate Change,” April 4, 2022, https://www.whitehouse.gov/omb/briefing-room/2022/04/04/quantifying-risks-to-the-federal-budget-from-climate-change/.

22. Alan Buis, “The Atmosphere: Getting a Handle on Carbon Dioxide,” October 9, 2019, https://climate.nasa.gov/news/2915/the-atmosphere-getting-a-handle-on-carbon-dioxide/.

23. Krepon, Winning and Losing the Nuclear Peace, pp. 523-525.

Kenneth C. Brill is a former acting U.S. assistant secretary of state for the Bureau of Oceans and International Environmental and Scientific Affairs, a former U.S. ambassador to the International Atomic Energy Agency, and founding director of the U.S. National Counterproliferation Center.

Dealing with this new threat to prosperity and stability will require a recognition that weapons of war are not the best defense against the most sustained threats of the 21st century and beyond. 

Reducing Tensions Over Nuclear Testing at Very Low Yield

November 2023
By Julien de Troullioud de Lanversin, Christopher Fichtlscherer, and Frank N. von Hippel

The U1a Complex is an underground laboratory at the U.S. Nevada National Security Sites where scientists conduct subcritical and physics experiments to obtain technical information about the U.S. nuclear weapons stockpile. (Photo courtesy of Nevada National Security Sites)Twenty-three years after Russia ratified the Comprehensive Test Ban Treaty (CTBT), Moscow is “unratifying” but not unsigning the pact as a by-product of its war on Ukraine and related tensions with the United States.1

Such a move would contradict Russia’s previously stated commitments to help bring the CTBT into force and is another body blow to the embattled international arms control regime.

Although China and the United States have not ratified the treaty, they have signed it, effectively abided by it, and with Russia and several other states, have anchored a de facto moratorium on nuclear testing. Recent accusations made by the United States, however, have cast doubts on whether Russia and perhaps China are still adhering to their moratoriums for certain types of tests at very low yields.

With increasing nuclear tensions between great powers, these suspicions could lead nuclear-weapon states to abandon their moratoriums and resume full-scale nuclear weapons tests. It is therefore imperative that they discuss a new transparency and verification regime for very low-yield tests.

China most likely is waiting for the United States to ratify the treaty, but without a major educational and lobbying campaign backed by the White House, most Republican senators could be expected to revert to the position of their caucus, which voted against CTBT ratification in 1999.2 For the CTBT to come into force, China, Russia, the United States, and six other specific countries still must ratify it.3

According to the Vienna Convention on the Law of Treaties, however, treaty signatures, unless they are withdrawn officially, obligate countries to comply with the treaty.4 All states other than North Korea have observed a testing moratorium since 1998, and North Korea has not tested since 2017.

In the absence of muffling in an enormous, mined cavity, the International Monitoring System of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) can detect nuclear tests of a yield of about 100 tons of TNT equivalent.5 That amount is less than 1 percent of the yield of the bomb dropped on Hiroshima. National and civilian seismic networks provide additional, more sensitive capabilities near former nuclear test sites. The CTBT, however, requires parties “not to carry out any nuclear weapon test explosion or any other nuclear explosion.”6 It is a “zero yield” treaty.

In 2016, China, France, Russia, the United Kingdom, and the United States issued a joint statement asserting “that a nuclear-weapon test explosion or any other nuclear explosion would defeat the object and purpose of the CTBT. ”7 According to the U.S. Department of State, the United States and the other governments participating in the CTBT negotiations agreed that the treaty “prohibits all nuclear explosions that produce a self-sustaining, supercritical fission chain reaction of any kind.”8 A fission chain reaction is called supercritical when it is exponentially growing and subcritical when it dies out. This interpretation of zero yield is commonly referenced as the U.S. zero yield standard.

An article-by-article analysis of the treaty submitted to the U.S. Congress by the Clinton administration in 1997 listed some explosive experiments that the U.S. nuclear weapons design laboratories would be allowed to conduct under the treaty. These include inertial confinement fusion experiments such as the laser-driven implosions of deuterium and tritium being carried out at the Lawrence Livermore National Laboratory’s National Ignition Facility and subcritical experiments with plutonium conducted underground in Nevada by the Livermore and Los Alamos national laboratories.9

Russian Defense Minister Sergei Shoigu (R, front) visited the Russian nuclear weapons test site Novaya Zemlya in August, adding to Russian-U.S. tensions over the testing issue. (Photo by the Russian Defense Ministry with location confirmed by The Middlebury Institute of International Studies)The U.S. government claims that China and Russia may be violating the U.S. interpretation of the treaty by carrying out supercritical tests in steel containment vessels underground. More than six decades ago, during the 1958-1961 test moratorium and the associated negotiations that ultimately produced the Partial Test Ban Treaty, the United States carried out very low-yield supercritical tests, which at that time were referenced as “hydronuclear” tests. The purpose of these experiments was to determine whether the fission “primaries” of some warheads recently added to the U.S. nuclear stockpile were “one-point safe.” A nuclear warhead is said to be one-point safe when no significant nuclear yield can be produced if the explosive around the plutonium pit is detonated at a single point by, for example, a bullet.

In these experiments, the amount of plutonium in the pit was reduced to a level where the pit was definitely one-point safe and then the plutonium was added back bit by bit. At each step, the explosive around the pit was detonated at what was believed to be its most sensitive point until there was a measurable fission yield or the one-point safety of the primary had been established. The increments of plutonium were kept small enough so that the fission energy released would be less than that released by one pound (about 0.5 kilograms) of TNT.10 The Soviet Union also conducted such tests, in large “Kolba” vessels designed to contain explosions with total energy yields (chemical explosive plus fission) up to 50 kilograms of TNT.11 Such low-yield tests would not be detected by the CTBTO off-site monitoring instruments.

There is little interest in hydronuclear experiments in the United States today. A 2012 discussion of hydronuclear testing by the U.S. National Academy of Sciences could not “identify any significant advantage that could accrue to a state testing at…very low levels (<1 ton [TNT equivalent]).”12 The nuclear weapons laboratories are confident in the one-point safety of U.S. nuclear warheads. The focus of the laboratories is instead on carrying out subcritical nuclear tests to verify that the plutonium metal behaves as required when imploded.

In a subcritical test, an assembly of plutonium is imploded inside a containment vessel, and neutrons are introduced into the imploded mass to initiate a fission chain reaction. Because the mass remains subcritical, the chain reaction dies away. With current technical limitations on how many initiating neutrons can be introduced into the imploded plutonium mass, planned U.S. subcritical tests would generate about 10 billion fissions,13 which would release about 0.3 joules of energy, roughly equal to what would be released by the detonation of about 0.1 milligrams of TNT.

The measurement equipment required to analyze such very low-yield experiments is costly. The U.S. National Nuclear Security Administration (NNSA) is installing a $2 billion, 100-meter-long electron accelerator in a tunnel in its 300-meter-deep underground U1a subcritical testing facility in Nevada. The electrons will produce high-energy X-rays in a target outside the containment vessel to image the interior of the imploding plutonium mass. Neutrons will be injected to start the subcritical chain reaction, and gamma rays from the fissions will be measured to determine the rate at which the chain reaction dies away and thereby the degree of criticality that has been achieved.14

In 2019, the director of the U.S. Defense Intelligence Agency publicly accused Russia of “probably not adhering to the nuclear testing moratorium in a manner consistent with the zero-yield standard.”15 In 2020 the U.S. State Department indicated in its annual report, Adherence to and Compliance with Arms Control, Nonproliferation, and Disarmament Agreements and Commitments, that this conclusion had interagency support: “Despite Russia renewing its nuclear testing moratorium in 1996, some of its activities since 1996 have demonstrated a failure to adhere to the U.S. zero-yield standard, which would prohibit supercritical tests.”16 The report stated that the evidence was classified. It also expressed concern that “lack of transparency” at China’s Lop Nur test site “raise[s] concerns regarding China’s adherence to its test moratorium, which China declared in 1996, judged against the U.S. [subcritical] ‘zero-yield’ standard.”

As noted above, a 2012 review by the U.S. National Academy of Sciences could not “identify any significant advantage that could accrue to a state testing at…very low levels(<1 ton [TNT equivalent]).” A possible motive for Russia and China to carry out very low-yield supercritical or hydronuclear experiments could be because the degree of criticality of imploded plutonium pits is much easier to measure in a supercritical test, which produces many more fissions than a subcritical experiment and therefore many more diagnostic gamma rays. If Russia and China are conducting supercritical tests, perhaps it is because they do not want to match the more than $2 billion the United States is spending on its underground electron accelerator and other diagnostic equipment required for subcritical tests.

One can only speculate how the U.S. intelligence community concluded that Russia has conducted more than one supercritical experiment since 1996. One possibility could be that satellite images of Russia’s Novaya Zemlya test site have revealed large containment vessels such as a Kolba vessel being taken into the testing tunnels.

Jill Hruby, administrator of the U.S. National Nuclear Security Administration, speaking at a recent Comprehensive Test Ban Treaty (CTBT) conference, says the United States has “no plans” to resume the nuclear testing it halted in 1992 but will conduct “subcritical experiments.” (Photo courtesy of NNSA)Once the CTBT comes into force, any state-party may request a short-notice, on-site inspection of an area where it believes that a nuclear explosion or even a supercritical test may have taken place. Given that none of the remaining states that must sign and/or ratify the treaty have done so in recent years, however, the CTBT entry into force is years away. In the meantime, it would be advantageous to develop and demonstrate technical confidence-building measures through new methods and protocols that could determine whether contained experiments involving fissile material are subcritical.

At the 2023 CTBTO Science and Technology Conference in Vienna, U.S. NNSA Administrator Jill Hruby, whose organization maintains U.S. nuclear warheads, offered voluntary U.S. transparency, thus creating the possibility for international cooperation.

We are open to hosting international observers for monitoring and verification research and development on our subcritical experiments…. We are also open to working with others to develop a regime that would allow reciprocal observation with radiation detection equipment at each other’s subcritical experiments to allow confirmation that the experiment was consistent with the CTBT. We have several well-considered technical ideas on how this could be effective…. I sincerely look forward to future engagement with Russia and China on participation in bi- or tri-lateral verification confidence-building measures and other technological interactions to support future arms control and nonproliferation agreements.17

To date, these transparency proposals do not appear to have been detailed publicly or transmitted in a written form, and the Russian and Chinese governments have not accepted or rejected the offer.

Yet, there is a technical method to determine the amount of fission energy released by a contained, very low-yield test months or years later, by measuring the gamma rays from the radioactive decay of fission products and from transmutation products produced in the steel containment vessel as a result of irradiation by fission neutrons (fig. 1).18 Because the yields of supercritical experiments are typically orders of magnitude larger than those of subcritical experiments, such measurements would provide relevant evidence of a breach of the U.S. interpretation of zero yield.

Note: The gamma rays are from the radioactive decays of plutonium, fission products produced by chain reactions in the plutonium, and radioactive isotopes produced in the steel alloy of the containment vessel (CV) by irradiation from neutrons emitted by the chain reactions. The lines are labeled by the energy of the gamma ray in thousands of electron volts, the designation of the decaying radioisotope and the half-life of that isotope (or the of its parent isotope when the emitting isotope is the decay product of a longer-lived radioisotope).These verification methods would not be much help if a country does not announce all contained underground experiments or if it simply buries its containment vessels, as is the current custom, making them unavailable for inspection. To enable the implementation of verification after the test, a host country would have to agree not to bury or entomb a containment vessel before it is subjected to international inspection.

Continuity of knowledge for each containment vessel could be ensured by monitoring the tunnels or shafts through which containment vessels and plutonium could be introduced into the underground experimental complex. Each containment vessel could be tagged19 or “fingerprinted”20 for later identification. It is possible that this process could be managed remotely for the most part by CTBTO inspectors. Such an arrangement might be supplemented by remotely monitored on-site seismic stations to detect and localize contained underground explosions. The United States already has demonstrated such capabilities at its test site.21

As of mid-October, neither China nor Russia had responded to the U.S. proposal for reciprocal transparency at the three countries’ test sites.22 Given the high level of tensions between Russia and the United States over the war in Ukraine and between China and the United States, and the fact that the United States has not yet transmitted a formal written proposal, that is not surprising. Hopefully, in the longer term, the U.S. offer will open a path out of the destructive debate over possible but inconsequential Russian and Chinese violations of the U.S. interpretation of the CTBT.



1. Guy Faulconbridge and Filipp Lebedev, “Russian Duma Takes First Step to Revoke Ratification of Nuclear Test Ban Treaty,” Reuters, October 17, 2023.

2. In 1999, all but two Republican senators voted against ratification of the Comprehensive Test Ban Treaty (CTBT), and all but one Democratic senator voted in favor. Craig Cerniello, “Senate Rejects Comprehensive Test Ban Treaty; Clinton Vows to Continue Moratorium,” Arms Control Today, September/October 1999, https://www.armscontrol.org/act/1999-09/press-releases/senate-rejects-comprehensive-test-ban-treaty-clinton-vows-continue.

3. Egypt, Iran, and Israel have not ratified the CTBT. India, North Korea, and Pakistan have not signed the CTBT. Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), “Status of Signature and Ratification,” n.d., https://www.ctbto.org/our-mission/states-signatories (accessed October 21, 2023).

4. Vienna Convention on the Law of Treaties, May 23, 1969, 1155 U.N.T.S. 331, art. 18.

5. National Research Council, “The Comprehensive Nuclear Test Ban Treaty: Technical Issues for the United States,” 2012, fig. 2-8.

6. CTBTO, “Comprehensive Nuclear-Test-Ban Treaty (CTBT),” n.d., https://www.ctbto.org/sites/default

7. Office of the Spokesperson, U.S. Department of State, “Joint Statement on the Comprehensive Nuclear-Test-Ban Treaty by the Nuclear Nonproliferation Treaty Nuclear-Weapon States,” September 15, 2015, https://2009-2017.state.gov/r/pa/prs/ps/2016/09/261993.htm.

8. Bureau of Arms Control, Verification, and Compliance, U.S. Department of State, “Scope of the Comprehensive Nuclear Test-Ban Treaty,” n.d., https://2009-2017.state.gov/t/avc/rls/212166.htm (accessed October 21, 2023).

9. “Comprehensive Nuclear Test-Ban Treaty: Message From the President of the United States,” 105th Cong., 1st sess., Treaty Doc. 105-28, p. 4 (“Activities not affected by the treaty”).

10. Robert N. Thorn and Donald R. Westervelt, “Hydronuclear Experiments,” Los Alamos National Laboratory, LA-10902-MS, February 1987, https://www.osti.gov/servlets/purl/6646692.

11. National Nuclear Center of the Republic of Kazakhstan, “Nuclear Tests Consequences Elimination. ‘Kolba’ Containers Preservation,” May 9, 2022, https://www.nnc.kz/en/news/show/346.

12. “[O]ne benefit a State might gain from such very low yield tests would be to improve one-point safety. Such a step would not, standing alone, impair U.S. security.” National Research Council, “Comprehensive Nuclear Test Ban Treaty,” p. 104 fn.

13. David John Funk, “Enhanced Capabilities for Subcritical Experiments (ECSE): Portfolio Overview,” Los Alamos National Laboratory, LA-UR-18-28253, March 11, 2019, p. 46, https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-18-28253.

14. U.S. Government Accountability Office, “Program Management Improvements Would Benefit U.S. Efforts to Build New Experimental Capabilities,” GAO-23-105714, 2023, p. 7.

15. Hudson Institute, “The Arms Control Landscape ft. DIA Lt. Gen. Robert P. Ashley, Jr.,” May 29, 2019, https://www.hudson.org/national-security-defense/transcript-the-arms-control-landscape-ft-dia-lt-gen-robert-p-ashley-jr.

16. U.S. Department of State, “Adherence to and Compliance With Arms Control, Nonproliferation, and Disarmament Agreements and Commitments,” June 2020, p. 50, https://www.state.gov/wp-content/uploads/2020/06/2020-Adherence-to-and-Compliance-with-Arms-Control-Nonproliferation-and

17. Jill Hruby, Remarks at the CTBT Science and Technology Conference 2023, June 19, 2023, https://www.energy.gov/nnsa/articles/remarks-nnsa-administrator-jill-hruby-ctbt-science-and-technology-conference-2023.

18. Julien de Troullioud de Lanversin, Christopher Fichtlscherer, and Frank N. von Hippel, “Onsite Verification of the Comprehensive Nuclear Test Ban Treaty at Very Low Yields,” n.d., https://resources.inmm.org/sites/default/files/2021-09/a325.pdf.

19. Keith M. Tolk, “Reflective Particle Technology for Identification of Critical Components,” SAND-92-1676C, n.d., https://www.osti.gov/servlets/purl/7116334.

20. See Johannes Strömbom, “Natural Fingerprinting of Steel,” Luleå University of Technology, 2021, https://www.diva-portal.org/smash/get/diva2:1568687/FULLTEXT01.pdf.

21. National Research Council, “Comprehensive Nuclear Test Ban Treaty,” pp. 74-75.

22. Jonathan Tirone, “U.S. Offers Nuclear-Test Inspections to Ease Russia, China Tension,” Bloomberg, September 28, 2023.


Julien de Troullioud de Lanversin is an assistant professor in the Division of Public Policy at Hong Kong University of Science and Technology. Christopher Fichtlscherer is a doctoral graduate student at RWTH Aachen University. Frank N. von Hippel is professor of public and international affairs emeritus at Princeton University’s Program on Science and Global Security.

Given rising nuclear tensions involving China, Russia, and the United States, it is imperative that key states discuss a new transparency and verification regime for very low-yield nuclear tests.

Russia, the CTBT, and International Law

November 2023
By David A. Koplow

The recent decisions by the Russian Duma regarding the 1996 Comprehensive Test Ban Treaty (CTBT) have generated considerable legal and policy confusion. This analysis is an attempt to clarify the nature and consequences of those actions under international law.

Russia’s process is not an exercise of the “supreme national interests withdrawal clause,” which is contained in article IX of the CTBT and is common in other arms control agreements. That provision, like the rest of the treaty, is not operational until the treaty enters into force, which has not occurred. Article IX cannot be relied on by any state under the current circumstances and is not the basis for Russia’s recent actions.Instead, the next reference point is the 1969 Vienna Convention on the Law of Treaties, which sets forth the provisions regarding the conclusion, operation, and interpretation of international agreements. Article 18 of the convention establishes two circumstances under which a state is obligated to “refrain from acts which would defeat the object and purpose of a treaty” before the treaty enters into force.

The exact scope of the CTBT’s “object and purpose” is debatable. In 2016 the five nuclear-weapon states recognized under the nuclear Nonproliferation Treaty, which are also the permanent members of the UN Security Council (China, France, Russia, the United Kingdom, and the United States), issued a joint statement in which they authoritatively affirmed that a nuclear test would defeat the CTBT’s object and purpose. The entire Security Council subsequently endorsed that interpretation in Resolution 2310.

The first circumstance in which this obligation is operational is detailed in Vienna Convention article 18(a), which addresses the interval between a state signing and ratifying the treaty. That is the situation in which China, the United States, and a few others now stand regarding the CTBT. This obligation applies until the state “shall have made its intention clear not to become a party to the treaty.”

The mechanism for a state to specify its intention not to ratify a treaty, often incorrectly referenced as “unsigning” the treaty, is what the United States exercised regarding the 1998 Rome Statute establishing the International Criminal Court and the 2013 Arms Trade Treaty. In those cases, by expressing the intention not to ratify, the United States was released from the obligation to refrain from acts that would defeat the object and purpose of those treaties.

Russia has ratified the CTBT, so its recent actions are not governed by article 18(a). Instead, article 18(b) provides the same obligation to refrain from acts that would defeat the treaty’s object and purpose during the interval between ratification and the treaty’s entry into force “provided that such entry into force is not unduly delayed.”

In principle, a state perhaps could declare  that the CTBT’s entry into force has been “unduly delayed.” The treaty was opened for signature in 1996, but is unlikely to enter into force in the foreseeable future. Yet, Russia has not cited “undue delay.” Instead, it complained about the U.S. failure to ratify the CTBT and activities at the U.S. nuclear test site. Hence, the convention does not provide the mechanism for Russia to “unratify” the CTBT.

State practice regarding other treaties has rarely been tolerant of a withdrawal of a ratification prior to the treaty entering into force. The secretary-general of the United Nations, the usual depositary for multilateral treaties, occasionally has allowed a state to rescind a ratification without reference to or authorization by the convention. That presumably is what would happen here.

The final piece of the puzzle turns back to article 18(a) and raises the question of whether Russia’s withdrawal of its CTBT ratification also should be treated as an expression of an intention not to ratify the treaty again in the future. If so, the Duma’s action also could be interpreted as an “unsigning” of the CTBT, releasing Russia from the obligation to refrain from acts that would defeat the treaty’s object and purpose. More likely, the withdrawal of Russia’s ratification would not be interpreted as carrying that double effect, so Russia still would be regarded as a CTBT signatory obligated under article 18(a). That interpretation is reinforced by Putin’s comments about seeking “parity” with the United States regarding the CTBT; both states would now be obligated to refrain from acts that defeat the treaty’s object and purpose, including the obligation not to conduct nuclear tests.

In sum, Russia’s withdrawal of its CTBT ratification is not contemplated by the CTBT or the Vienna convention. Yet, it is an accepted, rare practice under international law. Russia thereby will achieve its objective of mirroring the United States regarding each country’s status under the treaty.

The withdrawal of ratification most likely has no practical legal effect. Russia, like the United States, would still be obligated as a signatory to refrain from acts that would defeat the treaty’s object and purpose, including nuclear testing. To date, Russia has not indicated any intention to violate its obligation under the convention by terminating its national moratorium.

David A. Koplow is the Scott K. Ginsberg Professor of Law at the Georgetown University Law Center.


Even after withdrawing its ratification of the Comprehensive Test Ban Treaty, Russia would still be obligated to refrain from nuclear testing.

Using Multilateralism to Fill the Space Policy Vacuum

November 2023
By Il-hoon Kim

The first series of meetings of the UN open-ended working group on reducing space threats through norms of responsible behaviors and actions came to a close on September 1 with two agreements: that there was no agreement and that a compromise is beyond the horizon.

Countries are increasingly dependent on a widening array of satellites in space. (Photo courtesy of Northrup Grumman)In fact, not even the title of a procedural report could be agreed. Arguably, this stems from a fundamental difference of philosophy on how space security should be governed internationally. Despite the overwhelming support for the report among states and civil society representatives in the working group, a handful of states abused the working group’s consensus rule and blocked the report. These states maintained a single-minded position that only legally binding instruments are meaningful. They refused to accept that the novel approach of cultivating a set of responsible behaviors to address the threats in, to, and from outer space enjoys wide backing from the international community, as evidenced by the fact that UN General Assembly Resolution 76/231, which established the working group, was adopted on a vote of 150-8.1

Four rounds of the working group were organized to implement the mandate of the UN resolution. It called for taking stock of the existing international legal and other normative frameworks concerning threats arising from state actions with respect to outer space and considering current and future threats by states to space systems and actions, activities, and omissions that could be considered irresponsible. In addition, the working group was charged with recommending to the General Assembly possible norms, rules, and principles of responsible behaviors relating to threats by states to space systems, including how such recommendations might contribute to the negotiation of legally binding instruments and prevent an arms race in outer space.

Except for a handful of states that opposed the working group from its inception, the majority of delegations involved in the deliberations over the last two years expressed support for this open, inclusive, and substantive platform and its mission to forge a consensus on concrete ways to enhance space security with the participation of all stakeholders.2 In a joint statement made at the closing session of the working group, 39 participating states reaffirmed that “political commitments on responsible behaviors can be developed in support of, and without prejudice to, the pursuit of legally binding measures and instruments in this area” and insisted that “these two approaches are not mutually exclusive.” They also appreciated the working group as “an excellent starting point that complements others’ efforts related to enhancing outer space security,” including the newly established group of governmental experts on the prevention of an arms race in outer space.

Notwithstanding, states that opposed the General Assembly resolution clearly showed that they would not allow consensus. Their key arguments against a behavior-based approach included that only a legally binding instrument can guarantee security in outer space; that the term “responsible behavior” is too subjective, vague, and unclear; and that capabilities, not behaviors, should be the basis of discussion. In short, these states asserted that the negotiation of the draft Treaty on the Prevention of the Placement of Weapons in Outer Space and of the Threat or Use of Force Against Outer Space Objects is the only viable way forward.

As plausible as they may sound, these arguments are faulty. First, the blind pursuit of legally binding instruments alone cannot ensure binding solutions. The war in Ukraine, intensified by Russia’s full-scale invasion in 2022, is a clear example. What good is a law that is not respected and that cannot be enforced effectively? The world need not be reminded that North Korea promised never to produce or acquire a nuclear weapon when it joined the nuclear Nonproliferation Treaty (NPT) in 1985 at the urging of the Soviet Union, which provided Pyongyang with nuclear research reactors. Nevertheless, North Korea developed its nuclear programs, announced its withdrawal from the NPT in 2003, has advanced its nuclear weapons program, and conducted six nuclear tests in the 21st century. There are countless examples of states violating their legal commitments.

The subjective nature of "responsible behaviors” also should not be a barrier to exploring proposals with which nations can agree. There is no disagreement that international law and norms should be based on objectivity. Yet, the international community also must not chase rainbows, believing that there is such a thing as an absolute good or objectivity in international affairs. Many if not most existing international laws and norms result from iterative processes. The act of war itself was not prohibited and was not even regarded as an irresponsible act before the difficult lessons learned through World War II were translated into the UN Charter. In other words, the working group and other consensus-seeking efforts provide valuable platforms by which to exchange views, shape converging ideas, and collectively confer objectivity on the norms that states can agree to follow. In addition, the objectivity of law, whether domestic or international, must undergo subjective perception and interpretation by those who implement and enforce it. Laws themselves are not static either.

One proposed set of tenets for responsible behaviors in space was put forward by U.S. Spacecom in March. (Graphic by U.S. Spacecom)Finally, the nature of space—the speed at which events occur and the dual-purpose characteristics of space systems—make capability-based prohibitions and their verification extremely difficult if not impossible at this stage of technological development. To date, weapons of mass destruction are the only type of weapons that are prohibited under existing international law (the 1967 Outer Space Treaty) from being stationed in orbit around the Earth or other celestial bodies.3 The sole purpose of the weapons of mass destruction is quite clear: to inflict mass destruction. There is no peaceful or commercial application, so it is easier to impose a legal ban. On the other hand, commercial or civilian satellites can be used beyond their original purpose, for example, as bullets that can apply kinetic force against other space systems. Robot arms on one satellite can be used to put other satellites off orbit or destroy them altogether. Governance of space security must take into consideration all of these critical and realistic characteristics as a legal ban could unduly restrict peaceful uses.

This is why the idea of norms, rules, and principles of responsible behaviors to address space threats was proposed to the international community by a number of states. Security threats involve action or inaction by a state that is deliberate, but the nature of space makes it impossible to verify that deliberateness or intent. As a result, many countries, including South Korea, have been ardent supporters of addressing space security threats through observable behaviors rather than prohibiting dual-use capabilities. Such prohibitions inevitably will have restrictive effects on the legitimate development and use of space. Banning robot arms, for instance, would mean that this capability cannot be used even for peaceful purposes, such as repairing satellites or rescuing satellites in distress.

This concern about deliberate threats also differentiates the space security norms now under discussion by the working group from the existing space safety governance mechanism led by UN Committee on Peaceful Uses of Outer Space. The UN committee was established by the General Assembly in 1959 to review international cooperation on the peaceful uses of outer space, study space-related activities that could be undertaken by the United Nations, encourage space research programs, and study legal problems arising from outer space exploration. Opponents of the behavior-based approach have been critical of the fact that safety issues must remain under the UN committee purview and that duplicity must be avoided. Risks or hazards, meaning consequences not caused by deliberate actions that potentially arise from peaceful space development activities, should continue to be regulated by existing international legal instruments, including the five outer space treaties and frameworks such as the UN committee.4 Issues pertaining strictly to space traffic management and other matters that are covered under guidelines adopted by the UN committee in June 2018 would fall under this category.5

Although duplication undoubtedly should be avoided as much as possible, the difference in the membership between the respective mechanisms and the importance of security issues must be given due consideration. For instance, only 102 states are members of the UN committee. Space security will have ramifications for the wider world, not just for space-faring nations, considering the growing global dependence on services provided by various space systems. For instance, a country could decide to destroy its own satellites, but the resultant debris likely will endanger the space systems of other states. The debris also could have a prohibitive effect on areas of space that otherwise could have been utilized for peaceful purposes if not now occupied by long-lived debris. Such problems caused by debris creation may fall under the purview of the UN committee, but the actions that caused the problem have a security origin and therefore cannot be addressed fully by confining the discussions to the handling of the aftermath of such events.

Closing the vacuum of norms is expected to bring realistic, tangible benefits to humanity as a whole. Among the benefits identified in the draft report of the chair of the working group are reducing threats to international peace and security related to activities in outer space, contributing to negotiations on a legally binding treaty or other instrument to prevent an arms race and war in outer space, and contributing to the long-term sustainability of outer space activities and the continuing and nondiscriminatory use and exploration of outer space.

In addition, the draft report cited the benefits of reducing the risk of misunderstandings, misperceptions, miscalculations, and unintended escalation and conflict; encouraging transparency and communication regarding space activities to avoid misinterpretation; and ensuring that private actors are accountable for their actions in outer space and fostering cooperation between states and private actors in the protection of space systems. Other benefits included encouraging the development and deployment of new technology consistent with international law.6

The rapid pace of technological advances and the advent of the new space era has made outer space increasingly congested, contested, and competitive. Many states and much of the world’s population are reliant on services provided by space systems. As a result, it would be detrimental and perilous to leave outer space void of any norms to govern the security dimensions. Threats emanate in all four vectors: earth to space, space to space, space to earth, and earth to earth. Threatening activities include launching space vehicles without coordinating beforehand with potentially affected countries; conducting rendezvous and proximity operations without prior notification, coordination, or consent; and testing or using destructive direct-ascent anti-missiles. Other potential threats include deliberately interfering with the command and control of space systems or impairing the ability of an operator to control a satellite and jamming or spoofing the signals of positioning, navigation, and timing satellites or interfering with such systems via cyberspace or other means.

A majority of UN member states aspire to create legally binding instruments to this end. Yet as reflected in the chair’s draft report, many working group participants “reaffirmed that possible solutions to outer space security can involve a combination of legally binding obligations and non-legally binding measures, and that work in both of these areas can be further pursued in a progressive, sustained and complementary manner, without undermining existing legal obligations”7 while recognizing that such nonbinding measures are not a substitute for legally binding arms control instruments.

The NG-11 Cygnus spacecraft, which is used to resupply the International Space Station and host payloads for experiments and technology demonstrations, is among the systems that could be at risk if UN efforts to reduce space threats are not successful. (Photo courtesy of NASA)Even so, a handful of states maintain the position that there can be no other way but the legally binding way. Such an all-or-nothing approach is unrealistic in light of today’s international security and diplomatic realities. What is more concerning is that the technologically less developed and resourceful countries likely will bear the brunt of the damage and disadvantage arising from the vacuum of norms, rules, and principles because they will not be in position to protect their rare assets in space by themselves. As such, the handful of resistant states is preventing the international community from collectively safeguarding the world by addressing and mitigating current and future space-related threats. A few states have abused the rule of consensus to effectively veto anything that deviates from their own legally-binding instruments, including the title of the working group itself. What states ought to be engaging in is multilateral consensus-driven negotiations to reach agreements on vital issues of common interest, thus guaranteeing the peace and predictable governance of outer space.

In light of the gravity and urgency of this issue, the open and inclusive platform provided by the working group must continue. Although the group of governmental experts8 will begin on November 20 in Geneva and provide another useful platform for discussing security in outer space, its closed setting, allowing only 25 national representatives as expert participants, cannot substitute for the working group in which all UN member-states and civil society can participate.

The next working group will need to pursue further in-depth discussions on concrete measures to reduce space threats in the form of voluntary yet politically binding pledges. Nevertheless, should the rule of consensus once again prove prohibitive to forging viable agreement on norms, rules, and principles of responsible behaviors governing space security, the international community should consider manifesting their shared interest in the form of a cooperative group in which states participate voluntarily. The benefits of this partnership would be shared mutually by the participating states but not extended to nonparticipants. If those countries willing to act responsibly can agree on concrete measures that allow such benefit sharing and if nonadmission proves disadvantageous to nonparticipants, such a cooperative has the potential to eventually incorporate large numbers of countries, ultimately leading to a viable, relevant, and sustainable set of international norm, rules, and principles.

The benefits of these responsible behaviors could include many elements in the chair’s draft report: notifying and consulting each other before space launches, conducting rendezvous and proximity operations, jamming or spoofing of signals, refraining from any acts that would impair the provision of critical space-based services to civilians, and sharing information on possible breaches of such actions by private sector actors. Another important outcome of such a cooperative could be the establishment of routine channels of communications to share information and to continue shaping the list of responsible behaviors. Sharing of real-time information on space situational awareness through a joint project or joint burden sharing could be another exclusive benefit that can be reaped by participants.

This type of cooperation would be possible because, unlike most traditional arms control arrangements, the novel approach taken by the working group is based on behaviors and not capabilities per se. If prohibitions or restrictions on development, acquisition, deployment, testing, or use of certain space and counterspace capabilities become the focus, it would be extremely difficult to establish such norms because there always would be the fear of cheating by nonparticipants or even participants due to the lack of a verification regime. This is another important contribution that the working group approach can make to the shared international efforts.

What is most important is to continue this important work. Disagreement over the working group title prevented the release of an official report, but it should not derail the international community from getting back to the right orbit.

Norms alone are not the silver bullet that will solve all problems, but they are undeniably an indispensable component of future space security governance. As UN Secretary-General António Guterres rightly pointed out at the UN Security Council meeting on April 24, states must recommit to make the prevention of conflict and crises a priority. Outer space is a critical realm that requires the revival of multilateralism before the damage becomes irreversible and out of control.



1. The eight members in opposition were China, Cuba, Iran, Nicaragua, North Korea, Russia, Syria, and Venezuela.

2. For instance, 32 international organizations, commercial actors, and civil society organizations attended the working group, along with an open invitation for all UN member states. See UN General Assembly, “List of Other International Organizations, Commercial Actors and Civil Society Organizations Attending the Open-Ended Working Group, in Accordance With Resolution 76/231,” A/AC.294/2023/INF.2, August 31, 2023.

3. See Treaty on Principles Governing the Activities of States in the Exploration and
Use of Outer Space, Including the Moon and Other Celestial Bodies, January 27, 1967, 610 U.N.T.S. 205.

4. For example, see UN Office for Outer Space Affairs, “Status of International Agreements Relating to Activities in Outer Space,” n.d., https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties/status/index.html (accessed October 20, 2023).

5. Committee on the Peaceful Uses of Outer Space, “Guidelines for the Long-Term Sustainability of Outer Space Activities,” A/AC.105/2018/CRP.20, June 27, 2018.

6. UN General Assembly, “Draft Report of the Open-Ended Working Group on Reducing Space Threats Through Norms, Rules and Principles of Responsible Behaviours,” A/AC/294/2023/CRP.1/Rev.1, August 31, 2023.

7. Ibid., para. 7.

8. UN General Assembly, “Further Practical Measures for the Prevention of an Arms Race in Outer Space,” A/RES/74/34, December 18, 2019.

Il-hoon Kim, South Korea’s deputy permanent representative to the Conference on Disarmament in Geneva, is a former director of the Disarmament and Nonproliferation Division of the South Korean Ministry of Foreign Affairs. The author’s opinions are his own and may not reflect the position of the South Korean government.


Norms alone are not the silver bullet but they are an indispensable component of future space security governance.

A Not-So-Strategic Posture Commission

November 2023
By Adam Mount

For the first time since the collapse of the Soviet Union, U.S. nuclear strategy is at a crossroads.

The Congressional Commission on the Strategic Posture of the United States unveils its report on October 12 at the Institute for Defense Analyses in Washington. (Photo by Aliyah Averette of the Institute for Defense Analyses)The rapid expansion of China’s nuclear forces calls into question fundamental assumptions about how the United States can deter nuclear-armed adversaries. In this context, Congress appointed a bipartisan commission of 12 former government officials to assess the threat environment and make recommendations on the nation’s strategic posture. The final report of the Congressional Commission on the Strategic Posture of the United States, released in October, marks the start of an inchoate debate about how to respond to China’s buildup, the outcome of which will shape the U.S. nuclear arsenal for decades.

Although Biden administration officials clearly have articulated the challenge presented by China’s buildup, the 2022 Nuclear Posture Review presented a strategy to meet it.1 The commission’s report is the first attempt by an entity of the U.S. government to propose an answer to the problem of tripolar deterrence, defined by the former commander of U.S. Strategic Command as the need to deter “two nuclear-capable, strategic peer adversaries at the same time,”2 namely China and Russia. The Pentagon estimates that China’s deployed nuclear warheads have more than doubled since 2020, from 200 to 500, and projects them to more than double again by 2030.3 This increase, combined with expansions in Russian and North Korean nuclear forces, could double the number of nuclear weapons that U.S. forces are ordered to deter by 2035. The challenge is complicated by the need to deter what the commission calls “opportunistic or collaborative two-theater aggression.”

The problem of tripolar deterrence is far more complex than simple arithmetic. China’s buildup and the U.S. response pose significant risks to strategic stability, increasing the chance that adversaries could aggress against U.S. allies, that regional crises could advertently or inadvertently escalate to the nuclear level, and that limited nuclear use could expand into a strategic exchange. All other things being equal, a constant U.S. nuclear force cannot maintain the same strategy and hold twice the number of targets as it does now. Yet, U.S. strategy and other elements of the strategic posture do not need to be held constant. Developing a strategy to maintain strategic stability will require planners to assess a wide range of options, many of which present their own stability risks, fiscal or logistical challenges, or political problems when presented to U.S. allies and partners.

A Strategic Stability Strategy

One set of variables comprises nuclear posture: the numbers, types, positions, and alert status of U.S. nuclear forces. A strategy that depends solely on adjusting nuclear posture may ultimately succeed in holding the additional targets at risk, but may end up being unnecessarily slow or costly, may not help to deter other kinds of threats, or may inadvertently degrade strategic stability. A symmetrical response to China’s buildup is not necessarily the best response.

Many other variables could comprise critical parts of a strategy to maintain stability in the context of tripolar deterrence. For example, U.S. officials may consider how advanced conventional forces could help deter and respond to limited nuclear use in regional conflicts or affect a strategic exchange. Consistent with the Biden administration’s concept of “integrated deterrence,” officials may also seek to develop ways of imposing costs on an adversary by coordinating with allied nuclear or conventional forces or by using space, cyber-, economic, diplomatic, informational, or clandestine means to deny gains or impose costs.4 In many cases, non-nuclear options may be more flexible, credible, and less costly ways of producing the effects necessary to deter an attack.

In developing a strategy for tripolar deterrence, the U.S. president could also choose to adjust a range of parameters that structure nuclear planning, including the categories of assets that nuclear forces would target in specific contingencies, the quantity of damage required at different times after an enemy launches a strategic attack, the damage expectancy requirements attached to specific weapons systems against specific targets, or the level of risk they are willing to accept that a technological development could suddenly render a leg of the triad vulnerable. The president also may opt to issue updated guidance about how much risk he is willing to accept that an adversary could carry out a surprise disarming strategic attack or comes to doubt the credibility of available U.S. options for responding to limited nuclear use. Adjusting any of these parameters could change requirements for the number of U.S. weapons required to deter the growing arsenals of adversaries. Presidents customarily do not issue direct guidance on these kinds of specific parameters to affect nuclear planning, but they may have to do so if they intend to implement a deliberate strategy for tripolar deterrence.5

The first step toward a deliberate strategy of trilateral deterrence would be to reexamine, at a fundamental level, the purpose of U.S. nuclear weapons. The primary mission that determines the size and structure of U.S. strategic forces is to limit damage to the state and its allies should deterrence fail. A preemptive counterforce strategy, which depends on striking an adversary’s nuclear force before it is launched, is difficult to imagine for several reasons, not least of which is that, even in the best of circumstances, such a scenario would expose the U.S. homeland to several dozen nuclear attacks. A retaliatory counterforce strategy is equally problematic because, even in the best of circumstances, it would represent an attempt to limit damage after a catastrophic attack has already occurred. Any complete strategy for tripolar deterrence begins with answering these basic questions: Is damage limitation the primary mission of U.S. forces and, if so, how much damage and in what circumstances?

The Nimitz-class aircraft carrier USS Abraham Lincoln (CVN 72) and the Wasp-class Amphibious Assault Ship USS Kearsarge (LHD 3), showcasing an array of powerful U.S. military assets, sail during exercises in the Arabian Sea in 2019. A bipartisan congressional commission wants the United States to respond to two near-peer rivals, China and Russia, by building up more nuclear forces.  (Photo by Petty Officer 1st Class Brian Wilbur)Confronting these complex questions, the commission reached a simple answer: an across-the-board buildup of U.S. nuclear forces. Its report recommends pursuing increases in the size, diversity, and alert status of every nuclear system, including multiple warheads and road-mobile options for new intercontinental missiles, more cruise missiles, more bombers postured on continuous alert with more tankers to support them, more submarines, more capability to penetrate adversary air and missile defenses, and demanding requirements for new theater nuclear options to attempt to control escalations.

Despite evidence that development on homeland missile defense interceptors has stalled, the report recommends investing heavily in new programs and expanding their mission set beyond North Korea to include an ill-defined category of coercive attacks from Russia and China.6 Collectively, the proposals would reverse decades of initiatives from presidents of both parties to reduce reliance on nuclear weapons in favor of non-nuclear options that they considered more flexible. For the commission, tripolar deterrence is not a complex strategic problem but simply a deficit of nuclear weapons. Its answer to an arms race is an arms race.

The Commission’s Solution

The commission’s solution to the problem of tripolar deterrence is not a strategy. The report makes no attempt to specify the categories or numbers of targets that it believes must be held at risk and so does not provide estimates of how many additional systems to procure, when they will be required, or which to prioritize. The report rightly identifies a need to “deter or counter opportunistic or collaborative aggression” in multiple theaters, but it does not describe what this might look like or how it would affect U.S. plans and force requirements.7 Most importantly, the commission does not consider the significant risk that increases in U.S. nuclear forces could degrade crisis stability, thus increasing the risk of nuclear use. It is an arithmetic approach to the problem without the arithmetic.

Because it does not articulate its assumptions about what is required to deter U.S. adversaries, the report cannot explain why the commission believes current U.S. forces would be insufficient to inflict the required effects in relevant contingencies, the number of systems that would be required, or how a buildup in U.S. forces could meet their objectives given the likelihood that China and Russia would respond with further increases in their forces.8 The commission’s chapter on strategy states that “the basis for U.S. nuclear strategy is assured second strike,” but this standard cannot guide policy without an explanation of what they believe would constitute “unacceptable damage.”9 Adjustments to U.S. nuclear force structure could be part of a solution to the “two-peer problem,” but it is not a solution to suggest doubling the size of the U.S. arsenal without justifying the figure, as one commissioner did.10

The commission report also does not account for the major fiscal, logistical, and political constraints that would inhibit implementation of its recommendations. It acknowledges that its proposals “will drive extraordinary demands on the already-constrained” departments that manage the arsenal, but makes no attempt to offer recommendations that work within those constraints or realistic measures to loosen them.11 Instead, the report recommends a vast “overhaul and expansion of the capacity of the U.S. nuclear weapons defense industrial base” and the U.S. Department of Energy/National Nuclear Security Administration nuclear security enterprise and offers proposals that range from constructive to semantic to quixotic.12 Even if all of these specific steps were implemented, it is difficult to see how they add up to the enormous increase in capacity that would be required to enact the commission’s expanded force structure.

In practice, the commission’s answer to the two-peer problem will be far more influential on the gathering debate on the future of nuclear strategy than it is on actual U.S. policy. Because of the standing of the commission’s members and the political appeal of their findings, the commission’s answer likely will be accepted in many quarters as the default position. As the debate becomes detached from realistic options, it increases the risk that the United States never develops a coherent approach to the strategic challenge it faces.

The report should prompt a national debate on a strategy for tripolar deterrence. At present, no group has presented a viable alternative to a major expansion of the U.S. nuclear arsenal and its supporting infrastructure. In one recent article, three experts propose shifting away from targeting opposing warheads to targeting civilian infrastructure, which could be accomplished with relatively fewer warheads.13 This proposal is far out of step with the U.S. commitment to adhere to the law of armed conflict and so is unlikely to influence policy. By giving voice to the strawman constructed by advocates of a buildup, calls for countervalue targeting also does not help to promote a realistic debate on how to respond to the tripolar challenge.14 It may well be the case that an effective strategy for tripolar deterrence abandons any requirement for preemptive counterforce and accepts that assured second strike can be accomplished with a relatively smaller force, but the strategy must conform to the law of armed conflict to be implemented.

An effective strategy on tripolar deterrence will fall within the broad region between an infeasible buildup and an infeasible shift to civilian targeting. Developing that strategy will require reexamining some of the fundamental assumptions of U.S. nuclear strategy, including the value of damage limitation.

A constructive debate would consider not only the numbers and types of nuclear weapons in the U.S. arsenal, but it would explore how a broad set of variables can interact to enhance deterrence, ranging from the intricate parameters that guide nuclear planning to instruments in other domains of conflict.

Compelling recommendations will account for the significant and foreseeable constraints on U.S. options and the expected responses of adversaries. Most importantly, as the United States reevaluates its strategic deterrence posture, it should remember that its objective is to maintain strategy stability and reject policies that would degrade it.



1. Jake Sullivan, Remarks at the Arms Control Association Annual Forum, Washington, June 2, 2023, https://www.whitehouse.gov/briefing-room/speeches-remarks/2023/06/02/remarks-by-national-security-advisor-jake-sullivan-for-the-arms-control-association-aca-annual-forum/.

2. Aaron Mehta, “STRATCOM Chief Warns of Chinese ‘Strategic Breakout,’” Breaking Defense, August 12, 2021, https://breakingdefense.sites.breakingmedia.com/2021/08/stratcom-chief-warns-of-chinese-strategic-breakout/.

3. U.S. Department of Defense, “Military and Security Developments Involving the People’s Republic of China 2023: Annual Report to Congress,” October 19, 2023, https://media.defense.gov/2023/Oct/19/2003323409/-1/-1/1/2023-MILITARY-AND-SECURITY-DEVELOPMENTS-INVOLVING-THE-PEOPLES-REPUBLIC-OF-CHINA.PDF.

4. Stacie L. Pettyjohn and Becca Wasser, “No I in Team: Integrated Deterrence With Allies and Partners,” Center for a New American Security, December 2022, https://s3.us-east-1.amazonaws.com/files.cnas.org
; Adam Mount and Pranay Vaddi, “An Integrated Approach to Deterrence Posture,” Federation of American Scientists, n.d., https://fas.org/wp-content/uploads/2021/01/An-Integrated-Approach-to-Deterrence-Posture.pdf.

5. Sharon K. Weiner, “Resetting the Requirements for Nuclear Deterrence,” Arms Control Today, Vol. 52, No. 1 (2022): 12-16; Adam Mount, “The Biden Nuclear Posture Review: Obstacles to Reducing Reliance on Nuclear Weapons,” Arms Control Today, Vol. 52, No. 1 (2022): 6-11.

6. Congressional Commission on the Strategic Posture of the United States, “America’s Strategic Posture,” October 2023, p. 63, https://armedservices.house.gov/sites/republicans.armedservices.house.gov/files/Strategic-Posture-Committee-Report-Final.pdf.

7. Ibid., p. 31. See Keith B. Payne and David J. Trachtenberg, “Deterrence in the Emerging Threat Environment: What Is Different and Why It Matters,” Journal of Policy & Strategy, Vol. 2, No. 4 (2022): 3-51.

8. For a more modest, specific, and attainable response with a broadly similar approach to the commission, see Center for Global Security Research Study Group, “China’s Emergence as a Second Nuclear Peer: Implications for U.S. Nuclear Deterrence Strategy,” Lawrence Livermore National Laboratory, 2023.

9. Congressional Commission on the Strategic Posture of the United States, “America’s Strategic Posture,” p. 26.

10. “How Will America Deal With Three-Way Nuclear Deterrence?” The Economist, November 29, 2022.

11. Congressional Commission on the Strategic Posture of the United States, “America’s Strategic Posture,” p. 51.

12. Ibid., p. 60.

13. Charles L. Glaser, James M. Acton, and Steve Fetter, “The U.S. Nuclear Arsenal Can Deter Both China and Russia,” Foreign Affairs, October 5, 2023, https://www.foreignaffairs.com/united-states/us-nuclear-arsenal-can-deter-both-china-and-russia.

14. Keith B. Payne et al., “The Rejection of Intentional Population Targeting for ‘Tripolar’ Deterrence,” National Institute for Public Policy Information Series, No. 563 (September 26, 2023), https://nipp.org/wp-content/uploads/2023/09/IS-563.pdf.

Adam Mount is a nonresident senior fellow at the Federation of American Scientists.


For the bipartisan commission charged with recommending how the United States should deal simultaneously with two nuclear-capable adversaries, the “answer to an arms race is an arms race.”

Nuclear Ban Treaty Members to Meet in November

November 2023
By Shizuka Kuramitsu

States-parties to the 2017 Treaty on the Prohibition of Nuclear Weapons (TPNW) will hold their second meeting in New York on Nov. 27-Dec. 1. Amid the crisis facing the international arms control and disarmament regime, they are expected to review and continue implementing their plans for a total ban on nuclear weapons.

The TPNW, which entered into force on Jan. 22, 2021, bans states-parties from involvement in any nuclear weapons activities, including the use, threat of use, production, development, possession, and stationing of these weapons. Spearheaded by non-nuclear-armed states and civil society groups, the treaty originated from their frustration over the long stalemate among nuclear-weapon states to engage in serious nuclear disarmament as called for by the nuclear Nonproliferation Treaty (NPT).

At their first meeting, in June 2022, TPNW states-parties produced two documents aiming to advance the treaty, a 50-point action plan and a political statement. (See ACT, July/August 2022.)

They established three informal working groups to make progress during the intercessional period on important topics such as nuclear disarmament verification, victim assistance, environmental remediation, and universalization of the treaty. In addition, the action plan agreed to create a scientific advisory group, to implement gender provisions in the treaty, and to promote TPNW complementarity with existing treaties.

For the November meeting, each working group is preparing reports on their respective intersessional activities. The meeting is expected to issue a final document, according to the provisional agenda and government officials.

The “expectation of all the parties is to continue implementing the plans [and] having a meeting that reviews what was agreed in 2022 and its implementation,” María Antonieta Jaquez, coordinator for disarmament, nonproliferation, and arms control for the Mexican Foreign Affairs Secretariat, told Arms Control Today.

She suggested that the states-parties would continue following the 50-point action plan from 2022 because it “cannot be reinvented or rewritten every year.”

One key focus is universalization of the treaty. “The treaty has to continue growing,” Jaquez said. She emphasized that the participation of all TPNW states-parties, as well as states that remain outside the treaty, should be “all welcomed” and “it is important that we have as many stakeholders [join the treaty] as possible.”

Meanwhile, deepening geopolitical divides continue casting shadows over the nonproliferation and disarmament regimes. After the first TPNW meeting concluded, two NPT-related meetings failed to achieve a consensus and concluded with no substantive final documents (See ACT, September 2023.)

A contentious issue likely to be raised in November is how TPNW states-parties interpret the treaty provisions. In April 2023, Russia conducted a test launch of a missile that can carry nuclear warheads from a test site in Kazakhstan, an active TPNW member state. Although the treaty bans assistance with nuclear weapons development, it leaves the definition of “assistance” open to interpretation. Since the last meeting of states-parties, seven more states have signed the treaty, bringing the total number to 93 states, and four more states have ratified it, bringing the total to 69.

Juan Ramón de la Fuente Ramírez, Mexico’s ambassador to the United Nations, will serve as president of the second meeting of TPNW states-parties.

Working groups are expected to report on plans to advance nuclear disarmament verification, victim assistance, and other priorities.

Saudi Push for Enrichment Raises Concerns

November 2023
By Kelsey Davenport

In talks with the United States, Saudi Arabia is pushing for the right to produce nuclear fuel, a move that poses a greater proliferation risk given Riyadh’s threats to develop nuclear weapons.

Crown Prince Mohammed bin Salman of Saudi Arabia (C), inspecting an honor guard during the G20 summit in New Delhi in September, says that if Iran acquires a nuclear weapon, “we have to get one.” (Photo by Money Sharma/AFP via Getty Images)Saudi officials have said little publicly about its negotiations on a nuclear cooperation agreement with the United States, but the country has announced ambitious plans to expand its nascent nuclear program by purchasing two large nuclear reactors and enriching domestically mined uranium.

As a non-nuclear-weapon state-party to the nuclear Nonproliferation Treaty (NPT), Saudi Arabia can legally enrich uranium for peaceful purposes, but its interest in uranium enrichment is complicated by its threat to build nuclear weapons to match Iranian capabilities.

In a September interview with Fox News, Saudi Crown Prince Mohammed bin Salman said that if Iran acquires a nuclear weapon, “we have to get one.” Saudi officials have made similar comments in the past. (See ACT, April 2018.)

The Biden administration’s willingness to consider a Saudi enrichment program is a departure from long-standing U.S. policy to limit the spread of uranium enrichment and plutonium reprocessing by pressing states to forgo developing these technologies in nuclear cooperation agreements with the United States, known as 123 agreements.

A nuclear cooperation agreement is necessary under the 1954 Atomic Energy Act before certain U.S. technologies and materials can be sold abroad. As part of the agreement, states must meet certain criteria designed to prevent proliferation.

The nuclear negotiations predate a larger effort to normalize Israeli-Saudi relations. Saudi Arabia may be motivated to include the nuclear cooperation agreement in the broader rapprochement to gain Israel’s support for its nuclear ambitions.

Israel does not publicly admit to possessing nuclear weapons, but likely has an arsenal of about 80 warheads. The country is outspoken in opposition to other states in the region developing the capabilities to build nuclear weapons. Israeli Prime Minister Benjamin Netanyahu campaigned against the 2015 nuclear deal with Iran, citing the agreement’s provisions allowing Iran to enrich uranium as a key concern.

The Wall Street Journal reported in September that Netanyahu directed Israeli officials to work with the United States on an agreement that includes Saudi enrichment, but such a deal still would face criticism in Israel. Yair Lapid, a member of the Israeli Knesset and leader of the opposition to Netanyahu’s government, said in August that Saudi Arabia must not have “any level of enrichment.”

Although the effort to normalize Saudi-Israeli relations is on hold after Hamas terrorists attacked Israel on Oct. 7 and Israel retaliated by striking and blockading the Gaza Strip, Saudi Arabia is unlikely to abandon its nuclear plans.

But even if an agreement is reached, it is unclear if it will garner sufficient support in the U.S. Congress. If the agreement meets nine nonproliferation criteria set out in the Atomic Energy Act, it will enter into effect unless both houses of Congress pass a resolution of disapproval within 90 days.

If the agreement does not meet the nonproliferation criteria, Congress must pass a resolution of approval for it to enter into effect.

The nine nonproliferation criteria include a guarantee that any nuclear materials and equipment are not used for weapons development or other military purposes and that the recipient state has a comprehensive safeguards agreement in place with the International Atomic Energy Agency (IAEA).

Given Saudi Arabia’s public threats to develop nuclear weapons, it may be challenging for the Biden administration to gain support for any agreement that allows uranium enrichment, particularly if the kingdom does not have an additional protocol to its comprehensive safeguards agreement in place. Additional protocols to safeguards agreements were developed in the 1990s when it became clear from the cases of Iraq and North Korea that a comprehensive safeguard agreement alone was insufficient to prevent proliferation. An additional protocol gives the IAEA more access and information about a country’s nuclear activities.

Sixteen Democrats in the U.S. Senate sent a letter to Biden saying that the United States should “seriously consider” whether it is in its best interest to support a Saudi nuclear program. The Oct. 4 letter said that if the United States moves forward on a nuclear cooperation agreement, it should meet the “gold standard.”

The gold standard refers to a nuclear cooperation agreement that requires the receiving country to forgo enrichment and reprocessing and adhere to the additional protocol. The U.S. agreement with the United Arab Emirates meets the gold standard.

Congressional opposition to Saudi enrichment predates the current nuclear negotiations. During the Trump administration, Sen. Marco Rubio (R-Fla.) said that the United States “should suspend all talks” on a nuclear cooperation agreement “until the Saudi government agrees to the ‘gold standard’ requirements.” His statement followed the brutal murder of Saudi journalist Jamal Khashoggi by the Saudi government in October 2018.

Rubio and Sen. Ed Markey (D-Mass.) introduced legislation that would require any nuclear agreement with Saudi Arabia to meet the gold standard and secure an affirmative vote of approval from Congress. (See ACT, December 2018.)

The legislation did not become law, but it demonstrates the bipartisan opposition that Biden likely will face if he attempts to move forward on an agreement that does not meet the gold standard.

Saudi statements suggest that the country will not accept an agreement that bans uranium enrichment, but it is unclear if it would accept the more intrusive additional protocol to its safeguards agreement.

Saudi Arabia only announced in September during the annual IAEA General Conference that it would negotiate a comprehensive safeguards agreement with the agency. For years, the IAEA had been urging Saudi Arabia to update its safeguards.

Until Saudi Arabia adopts its safeguards agreement, IAEA monitoring is based on an outdated safeguards model, called the small quantities protocol, designed for states with little or no nuclear materials. That protocol was designed in the 1970s, but after determining it was insufficient, the IAEA revised it in 2005 to give the agency more tools for conducting safeguards. Saudi Arabia never adopted the revised text.

Although Saudi Arabia’s announcement that it will adopt a comprehensive safeguards agreement is a necessary step toward introducing nuclear materials, the country’s unwillingness to update its safeguards promptly in response to agency requests raises concerns.

In September 2020, IAEA Director-General Rafael Mariano Grossi said Saudi Arabia’s small quantities protocol is simply “not adequate.”

Saudi Arabia also forged ahead with constructing a research reactor under the outdated safeguards arrangement, a move that makes it more difficult for the IAEA to verify the reactor design and develop a safeguards approach. Standard practice is to allow the agency to inspect a reactor as it is being built.

The Biden administration has other options to reduce the risk of Riyadh using a civil nuclear program for weapons purposes besides insisting on the gold standard or forging an agreement allowing Saudi Arabia to enrich uranium.

It could attempt to bypass the question of Saudi enrichment by pursuing a black box approach, by which the United States would construct and operate a uranium-enrichment facility on Saudi soil. But it remains unclear how the United States would respond to any Saudi attempts to nationalize the facility or prevent the kingdom from acquiring knowledge about enrichment even if the facility was operated by U.S. personnel.

Furthermore, it may be challenging for the United States to implement such a proposal. The only U.S.-based and -operated enrichment facility, Centrus, just began operations in October. The only other commercial enrichment facility in the United States is operated by Urenco, a European-based enrichment consortium.

Another option would be to delay determining whether Saudi Arabia will be allowed to enrich uranium. The United States pursued a similar approach in its nuclear cooperation agreement with South Korea, when Seoul sought permission to reprocess spent nuclear fuel.

Delaying the decision would allow the United States and Saudi Arabia to study the feasibility and proliferation implications and consider alternative arrangements, such as U.S. support for a fuel fabrication facility in Saudi Arabia. This would allow Saudi Arabia to produce nuclear fuel with less proliferation risk because it would not include uranium-enrichment technology on Saudi soil.

A delay would also give Saudi Arabia time to determine if mining its uranium deposits is a viable option.

In January 2023, Saudi Energy Minister Prince Abdulaziz bin Salman said that the country intends to “utilize its national uranium resources” and pursue “the entire nuclear fuel cycle,” including “the production of yellowcake, low-enriched uranium and the manufacturing of nuclear fuel both for our national use and of course for export.” (See ACT, March 2023.)

But a joint publication by the IAEA and the Nuclear Energy Agency, a multilateral entity run out of the Organization for Co-operation and Economic Development in Paris, in 2023 assessed that mining Saudi Arabia’s uranium deposits would be “severely uneconomic.”

Given Saudi Arabia’s threats to develop nuclear weapons, it may be challenging for the country to purchase uranium ore for enrichment.

The Biden administration’s willingness to consider a Saudi uranium enrichment program departs from long-standing U.S. policy to limit the spread of uranium enrichment and plutonium reprocessing.


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