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Hiroshima Survivor
June 6, 2016
Negative Security Assurances After Russia’s Invasion of Ukraine
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July/August 2022
By Francesca Giovannini

On February 24, the international community took a catastrophic blow. Already battered by two years of the COVID-19 pandemic and deteriorating interstate relations, it stood in horror as Russian forces unleashed an unprovoked war on a neighboring country. Russia’s decision to invade Ukraine and reject Ukraine’s very existence as a separate state is ominous and highly momentous for the future of the world order.

A worker on a Ukrainian military base in 2006 cuts the nose off the last of Ukraine's Tupolev-22M3 bombers, also known as the "Backfire", a Soviet-made nuclear-capable strategic aircraft. A total of 60 aircraft were destroyed as part of an agreement under which Ukraine gave up nuclear weapons on its territory to Russia in return for security assurances that have now been violated. (Photo by Sergei Supinsky/AFP via Getty Images)The immediate consequences have been easily observable. More than seven million refugees have now crossed borders into other neighboring states, and many more remain internally displaced without supplies and assistance. Almost all major Ukrainian cities have been destroyed, and now a global food shortage is looming if agricultural exports from Ukraine and Russia are not promptly resumed. The long-term consequences might be, if possible, even more catastrophic.

There are legitimate growing concerns that Russia’s invasion of Ukraine might herald a new era of territorial conquest. Whether the norm of territorial sovereignty is upended or endures largely depends on whether the international community as a whole, not only the Western bloc, decides to rebuff and isolate Russia. So far, the reaction against Russian President Vladimir Putin’s power grab has been lukewarm at best in many world capitals.1

The significance of the Russian invasion is even more acute if analyzed through the lens of nuclear weapons. More than any other non-nuclear-weapon state except Belarus and Kazakhstan, Ukraine, received through the 1994 Budapest Memorandum, an unprecedented set of tailored negative security assurances from Russia, the United Kingdom, and the United States, the three depositary states of the nuclear Nonproliferation Treaty (NPT). These assurances were extended at the time of Ukraine’s accession to the NPT as a potent political reward in support of the country’s decision to become a non-nuclear-weapon state by eliminating all nuclear weapons from its territory.

Thirty years later, the country has been set ablaze by the Russian army. Europe and the world are now held hostage by a Russian president willing to resort to the threat of nuclear weapons use. As the war in Ukraine rages on, it is fair to ask, Do negative security assurances mean anything at all in the age of irresponsible nuclear-armed states?

A Patchwork Regime

For years, as they sought to establish a collective norm that would allow a more predictable coexistence with nuclear-armed states,2 non-nuclear-weapon states have demanded negative security assurances as binding commitments from nuclear-weapon states not to threaten and not to use nuclear weapons against their territory.

As George Bunn once remarked, “Since the first attempts to negotiate the [NPT], security assurances to [non-nuclear-weapon] states have been considered an important component of a credible worldwide nuclear nonproliferation regime. They have been viewed by [non-nuclear-weapon states] as one of their major requirements for achieving an adequate balance between their obligations and those of nuclear-weapon states.”3 Achieving a universal regime of negative security assurances proved difficult from the start. The first UN Security Council resolution on security assurances passed with the support of the Soviet Union, the UK, and the United States and simply committed the signatory countries to provide assistance to any non-nuclear-weapon state coming under a nuclear attack.4

Over time, a patchy regime of negative security assurances has emerged although it remains incoherent, fragmented, and as the Ukrainian case demonstrated, profoundly inadequate to provide the kind of reassurances that non-nuclear-weapon states might require in a highly unpredictable global nuclear order.5 Today, there are four main mechanisms by which assurances are granted to a non-nuclear-weapon state: The UN Charter, unilateral pledges by nuclear-armed states, no-first-use policies, and regional nuclear-weapon-free-zone treaties.

Article 2(4) of the UN Charter prohibits UN member states from using force against the territorial integrity or political independence of another state or in any other manner inconsistent with the purposes of the United Nations. The charter should serve theoretically as the most authoritative guarantee. Yet, the irony of entrusting the five acknowledged nuclear-weapon states, which are also permanent members of the UN Security Council, to act as the main global security guarantors can be hardly missed. Although the charter in principle gives all member states a guarantee against threats to and attacks on their territory and sovereignty, the reality is that many such threats and attacks have occurred since the UN was founded. If states are worried about being threatened by states armed with nuclear weapons, the fact that each of the five acknowledged nuclear-armed states has a veto in the Security Council hardly offers much confidence that the council will be able to address a threat emanating from one of them.

Nuclear-armed states have also provided unilateral pledges that are important but also qualified upon specific conditions.

The 2018 U.S. Nuclear Posture Review provides negative security assurances by stating that the United States “will not use or threaten to use nuclear weapons against non-nuclear-weapon states that are party to the NPT and in compliance with their nuclear nonproliferation obligations.” The document added the qualification that the United States reserves the right to amend its negative assurance if warranted by “the evolution and proliferation of non-nuclear strategic attack technologies.”6

Russia has made notable changes to its nuclear doctrine. For example, in 1993, to mitigate its own conventional military weaknesses, Russia adopted a defense posture heavily reliant on nuclear weapons and rejected the Soviet-era no-first-use pledge. Ever since, the Russians have reserved the right to use nuclear weapons in response to an attack involving any weapon of mass destruction or in response to conventional attacks “when the very existence of the state is under threat.”

France and the UK have opted for strategic ambiguity and have left open the possibility of using nuclear weapons against non-nuclear-weapon states in specific cases, including in response to weapons of mass destruction (WMD) threats or to an attack from a state acting “in association or alliance with a nuclear-weapon state.”7

Unlike other nuclear-armed states, China and India have adopted no-first-use pledges but it is unclear how long they will maintain them. As Steve Miller has argued, if a no-first-use policy “is to be more than a declaratory policy, then it must be meaningfully reflected in the war planning and force postures of the nuclear powers. Because the possibility of first-use inheres in the possession of a nuclear arsenal, it is not easy to create a posture that effectively displays genuine fidelity to the [no-first-use] pledge.”8 Miller has suggested several steps to make a no-first-use commitment more than just an empty statement, yet none of these steps is necessarily irreversible and permanent in nature. No-first-use policies are malleable depending on the needs of nuclear-armed states and the context in which they operate.

Regional nuclear-weapon-free zones offer more protection in that they contain a nonuse additional protocol that binds nuclear-weapon states not to use or threaten to use nuclear weapons against state-parties to a zone treaty. As Leonard Spector and Aubrie Ohlde suggest, “Non-use guarantees provided in the latter context offer NPT non-nuclear-weapon states one crucial advantage in comparison to more generalized, unilateral negative security assurances: There is no question that, if a [zone] treaty is in force, duly ratified protocols to that treaty are legally binding vis-à-vis the zonal parties.”9

The record of the regional nuclear-weapon-free-zone treaties is promising but mixed. The Treaty of Tlatelolco, affecting Latin America and the Caribbean, is the only one that has been ratified by all nuclear-weapon states. The impediments facing the others can be seen in the case of the United States. Although the United States signed additional protocols for the remaining zone treaties and submitted them to the U.S. Senate for ratification, the protocols are unlikely to be concluded soon given increasing U.S. political polarization.10

Even when a nuclear-weapon state ratifies a zone treaty, the commitment usually comes with qualifications that shrink the legal protection offered by the treaty.11 For example, in ratifying the additional protocols of the Africa-focused Pelindaba Treaty, France specified that nothing in “the protocols or the articles of the treaty shall impair the full exercise of the right of self-defense” as provided in article 51 of the UN Charter.12

Similarly, the UK imposed conditionality on its ratification of the Central Asian nuclear-weapon-free zone, arguing that it “reserve[s] the right to exercise the right to withdraw from the Protocol under Article 6, or where [it] considers that the threat, development and proliferation of other weapons of mass destruction, for example chemical and biological, make it necessary.

The case of the Southeast Asia Nuclear-Weapon-Free-Zone Treaty also reveals the insurmountable obstructionism of nuclear-weapon states when regional power projection is at stake. Since 1995, the Association of Southeast Asian Nations has been negotiating with the nuclear-weapon states to achieve ratification of the treaty protocols, but none of the five has done so. They claim that the treaty extends protection over continental shelves and exclusive economic zones, thereby potentially limiting port visits or landing rights for foreign vessels and aircraft.13 In a time of great-power competition and the U.S. pivot to Asia, it is plausible to argue that the fate of this treaty will remain in limbo for years to come.

All existing mechanisms are important but deemed insufficient even by many non-nuclear-weapon states. Several official statements over the years pointed out the need for a more comprehensive, legally binding multilateral treaty. During the opening of the 2010 NPT Review Conference, the official statement of the Non-Aligned Movement (NAM) reiterated “the importance of concluding a universal, unconditional, and legally binding instrument on negative security assurances to the non-nuclear-weapon states as a matter of priority, pending the total elimination of nuclear weapons.”14

In 2015 the NAM argued even more forcefully that “pending the total elimination of nuclear weapons, it is the legitimate right of all non-nuclear-weapon states-parties to receive effective, universal, unconditional, non-discriminatory, and irrevocable legally binding security assurances against the use or threat of use of nuclear weapons under all circumstances.”15

Finally, in a working paper tabled for the upcoming 10th NPT Review Conference in August, Algeria called for states-parties to “reaffirm the right of non-nuclear-weapon states to credible security assurances to ensure their security and sovereignty against the use, or threat of use, of nuclear weapons while awaiting nuclear disarmament.”16

The War’s Impact on Ukraine

Russia’s violation of Ukrainian sovereignty marks an inflection moment in the delicate relationship between nuclear-armed states and the rest of the international community and “sets a dangerous precedent by abrogating a longstanding convention and undermining the wider framework of security assurances and guarantees that nuclear-weapons states offer to non-nuclear-weapon states.”17

Although given security guarantees in 1994 when it gave up Soviet-era nuclear weapons on its territory, Ukraine today is in the fifth month of an unprovoked war by Russia that has killed thousands of civilians and destroyed countless cities. In photo, rescuers evacuate the body of a person from a building in Sergiyvka, near Odessa, that was hit by a missile strike on July 1, according to the Ukrainian emergency services. (Photo by Oleksandr Gimanov/AFP via Getty Images)As the war in Ukraine rages on, experts are debating how it will affect the security calculations of non-nuclear-weapon states. Some experts have claimed that the Russian invasion, if successful in its scope, could set a dangerous precedent so as to embolden other nuclear-armed states to launch military campaigns to conquer neighboring countries. The case of China over Taiwan is front and center in these specific discussions.

In a scenario where nuclear-armed states become increasingly predatory, non-nuclear-weapon states could seek protection by joining existing nuclear alliances. The hasty accession of Finland and Sweden to NATO seems to validate this argument. Yet, it is unclear how much political appetite exists in the United States to further expand nuclear guarantees to countries not already under the protection of U.S. nuclear extended deterrence.

Alternatively, the ruthless way in which Russia has chosen to disregard its commitments to Ukraine’s territorial sovereignty and the glibness with which its leaders threaten the use of nuclear weapons today may prompt countries with advanced nuclear know-how to pursue or fast-track the development of their individual nuclear capabilities. The path to the bomb is not easy or cost free, however, and is not a choice that any country can pursue lightheartedly.

A more likely, less discussed, but equally consequential scenario is that the war in Ukraine will deepen alienation, grievances, and mistrust among non-nuclear-weapon states. Such estrangement could lead to even more fierce political obstructionism against any new nuclear policy and a dangerous institutional paralysis across multiple institutions. This scenario is not one the international community can afford to face.

Rethinking Negative Security Assurances

Nuclear weapons-possessing states, especially the five acknowledged by the NPT, have often defined themselves as responsible guardians of the nuclear order. Yet, from the perspective of many non-nuclear-weapon states, history is riddled with examples of lawless behavior by nuclear-weapon states that, hiding behind the shield of their nuclear arsenals, have embarked on senseless military adventures without ever being held accountable. If anything, the war in Ukraine has validated the security concerns harbored by many non-nuclear-weapon states and further exacerbated their mistrust of the current nuclear order.

In such a precarious moment, there needs to be an urgent rethinking of the relationship between the nuclear-armed states and the rest of the international community by launching and sustaining a global dialogue with the goal of developing a new regime of universal, unconditional negative security assurances as a first concrete step. This regime will build on the existing mechanisms while expanding the responsibilities of nuclear-armed states and deepening their accountability.

Specifically, the new regime should start with a UN Security Council resolution declaring that honoring unilateral pledges of negative security assurances is a precondition to maintaining veto power in the council. The UN General Assembly should then agree to convene a special session every year in which all nuclear-armed states recommit to universal, unconditional negative security assurances to be delivered during the annual meeting of its First Committee. Finally, the UN Economic and Social Council should adopt a resolution stating that all regional trade agreements concluded in regions with nuclear-weapon-free zones should include a clause obliging all nuclear-armed states to honor the commitment to nonuse and nonthreat of nuclear weapons. Even the simple threat of nuclear weapons use could be sufficient to invalidate a regional trade agreement if the regional contracting parties choose to do so.

To enhance the existing regime of negative security assurances, it is critical for the UN to take a leading role. For too long, discussions about negative security assurances have been relegated almost exclusively to the domain of the NPT review conferences. Yet, as the Ukraine war demonstrates, in an age of predatory nuclear-weapon states, protecting non-nuclear-weapon states from the threat of nuclear weapons has to be a priority for the international community. In addition and perhaps most promising, the Ukraine war is bringing about significant changes in the power distribution within the UN itself for the benefit of non-nuclear-weapon states.

In the aftermath of the UN Security Council’s inaction over the Ukraine invasion, the General Assembly on April 26 adopted a resolution aimed at holding the council accountable for its use of vetoes. The resolution grants power to the General Assembly president to convene a formal meeting of all 193 UN members to demand an explanation when a veto is exercised by one or more Security Council members and the results undermine the UN’s role in maintaining global peace and security. By itself, the resolution may not be radical, but it comes amid an expanding movement demanding significant reforms, including more democratization in UN operations. For the first time, UN members are insisting on more accountability from the nuclear-weapon states that hold veto power in the council. A coalition of countries could take the discussion further and work with the General Assembly on an initiative that links the veto power of the five permanent Security Council members to the provision of negative security assurances to the international community.

Trainees prepare for combat formation training in June in New Taipei City, Taiwan. More Taiwanese citizens are seeking gun training amid concerns of possible military action against the self-governing island by China, which experts say could be emboldened by Russian aggression against Ukraine. (Photo by Annabelle Chih/Getty Images)It is equally essential for all nuclear-armed states, not just the acknowledged five, to reaffirm their commitment annually to honor universal, unconditional negative security assurances to all non-nuclear-weapon states. Demanding accountability from all nuclear-armed states is critical if non-nuclear-weapon states want to establish and maintain a universal regime of security assurances. In this regard, it would be also important for the UN General Assembly to launch consultations between nuclear-armed states and the rest of the international community. An existing proposal that is part of the Stockholm Initiative for Nuclear Disarmament calls for nuclear-weapon states “to deepen discussions on nuclear doctrine and declaratory policies, both among themselves and with the Non-Nuclear-Weapon States, at the upcoming NPT Review Conference and throughout the next NPT review cycle.”18

Finally, the new negative security assurance regime should aim to rebalance the enormous power asymmetry between nuclear-armed states and non-nuclear-weapon states. Such an asymmetry makes it challenging to keep nuclear-weapon states accountable. To do this, negative security assurances must be linked to domains that non-nuclear countries can reasonably control.

One such domain is economics. For countries seeking to receive negative security assurances, a possible way forward is to integrate these assurances into any economic agreement they sign with nuclear-weapon states. Given the disruption caused by the COVID-19 pandemic and the vulnerability of the supply chain, economic agreements, especially those with natural resource-endowed countries in the global South, are crucial for many nuclear-weapon states. Linking security and economic demands could make compliance by nuclear-armed states more likely. An important study on the relationship between the United States and its allies notes that “statistical studies of extended deterrence have found that political and economic connections between a deterrer and its protégé are a good indicator of the interests at stake for the deterring state. The greater the ties the more likely extended deterrence is to succeed.”19

The Limits of Security With Nuclear-Weapon States

These proposals probably would not have halted Putin’s plan to conquer Ukraine. In fact, it is reasonable to assume that, in high-stakes crises, almost nothing will cause a predatory nuclear-weapon state to change course. In addition, some of these proposals could be too costly for non-nuclear-weapon states that seek commercial deals with countries such as China and the United States. In some instances, countries in the global South may decide it is more important to sign trade agreements with great powers than to gain negative security assurances.

Finally, it will be argued that, after Ukraine, the time of progressive confidence-building steps between nuclear-armed states and the rest of the world has passed, that nuclear disarmament is more urgent than ever, and that efforts to achieve it should take precedence over modestly ambitious proposals. Although not wrong, in a time of great insecurity and higher nuclear risks, something ought to be done to bring together these two groups that have drifted further apart.

Establishing a process of confidence building between nuclear-weapon and non-nuclear-weapon states over the right of non-nuclear-weapon states to live in peace without the menace of nuclear weapons is an important starting point and something within reach. As a German official stated in a recent meeting,

In our eyes the rationale for moving forward with [negative security assurances] is simple: [they] serve as an important intermediary step on the way towards a world free of nuclear weapons and therefore constitute a concrete element of a step-by-step approach to nuclear disarmament. But they are—if granted and implemented in good faith—per se also an element of risk reduction in the overall strategic environment and a practical contribution to increasing confidence and trust in international relations.20

The pursuit of a nuclear-weapon-free world remains critical, indispensable, and non-negotiable. Yet, at this historical juncture, where near-anarchy reigns and normative principles are being lost, the international community must fully honor the request of many countries to be spared death by nuclear weapons.



1. Tanisha M. Fazal, “The Return of Conquest? Why the Future of Global Order Hinges on Ukraine,” Foreign Affairs, May/June 2022, https://www.foreignaffairs.com/articles/ukraine/2022-04-06/ukraine-russia-war-return-conquest.

2. “Nuclear-armed state” refers to all nuclear-weapon states, those within the nuclear Nonproliferation Treaty (NPT) and those outside.

3. George Bunn and Roland M. Timerbaev, “Security Assurances to Non-Nuclear Weapons States,” The Nonproliferation Review, Fall 1993, p. 11, https://www.nonproliferation.org/wp-content/uploads/npr/buntim11.pdf.

4. UN Security Council, S/RES/255, June 19, 1968.

5. The first set of negative security assurances was ultimately delivered by the United States, the United Kingdom, China, and the Soviet Union in the face of mounting pressure during the First Special Session of the UN General Assembly in 1978, but the statements were not harmonized and differed in scope and language. China’s statement was unconditional. The Soviet Union granted negative security assurances to non-nuclear-weapon states that did not host nuclear weapons on their territory. The UK and the U.S. statements delivered negative assurances, but made them conditional. Possible use of nuclear weapons was envisaged in case of an “attack from a nonnuclear weapon state against the territory of the UK and of the United States.” https://documents-dds-ny.un.org/doc/UNDOC/GEN/NR0/753/40/IMG/NR075340.pdf?OpenElement

6. Arms Control Association, “Nuclear Declaratory Policy and Negative Security Assurances,” March 2022: https://www.armscontrol.org/factsheets/declaratorypolicies#:~:text=These%20%E2%80%9Cpositive%E2%80%9D%20and%20%E2%80%9Cnegative,from%20pursuing%20nuclear%20weapons%20themselves.

7. Global Britain in a Competitive Age, The Integrated Review of Defense, Security, Development and Foreign Policy, March 2021: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/975077/Global_Britain_in_a_Competitive_Age-_the_Integrated_Review_of_Security__Defence__Development_and_Foreign_Policy.pdf

8. Steve Miller, paper produced for an internal meeting of the Pugwash Conferences on Sciences and World Affairs, October 2018. In the paper, Miller recommends making no-first-use pledges more credible by lowering the readiness of the nuclear force and eliminating specific nuclear capabilities such as nonstrategic nuclear forces.

9. Ibid.

10. The protocol to the South Pacific Nuclear Free Zone Treaty was submitted on May 2, 2011. S. Treaty Doc. No. 112-2 (2011). The protocol to the African Nuclear-Weapon-Free Zone Treaty was submitted on May 2, 2011. S. Treaty Doc. No. 112-3 (2011). The protocol to the Treaty on a Nuclear-Weapon-Free Zone in Central Asia was submitted on April 27, 2015. S. Treaty Doc. No. 114-2 (2015).

11. George Bunn, “The Legal Status of U.S. Negative Security Assurances to Non-Nuclear Weapon States,” The Nonproliferation Review, Vol. 4, No. 3 (Spring-Summer 1997): 1; George Bunn and Roland M. Timerbaev, “Security Assurances to Non-Nuclear-Weapon States: Possible Options for Change,” PPNN Issue Review, No. 7 (September 1996), p. 1.

12. UN Office for Disarmament Affairs, “France: Signature of Protocol III to the Pelindaba Treaty,” 2021, https://treaties.unoda.org/a/pelindaba_3/france/SIG/african_union.

13. Surya Subedi has argued that the Southeast Asian Nuclear Weapons Free Zone does not in any way contradict or challenge the Convention on the Law of the Sea nor does it impede freedom of passage. He notes, that “since Article 2(2) makes it clear that nothing in the Bangkok Treaty shall prejudice the rights of States under the [convention], the whole question of the transport of nuclear weapons through the Southeast Asian NWFZ depends on how the rules of the law of the sea, especially the provisions of the [convention], are interpreted. From this perspective, the Bangkok Treaty seems to alter little so far as the freedom of navigation, the right of innocent passage, the right of transit passage and the right of archipelagic sea lanes passage are concerned. The concern of the nuclear Powers about the effects of an NWFZ for Southeast Asia seemed to have stemmed because of the tendency of certain States of the region to interpret narrowly the right of transit and archipelagic sea lanes passage. The language of the Southeast Asia Nuclear-Weapon-Free-Zone Treaty in no way contradicts international treaties such as the Law of the Sea.” In Surya Subedi, Problems and Prospects for the Treaty on the Creation of a Nuclear Weapons-Free Zone in Southeast Asia, International Journal of Peace Studies, Volume 4 No 1, 1999, https://www3.gmu.edu/programs/icar/ijps/vol4_1/subedi.htm.

14. R.M. Marty M. Natalegawa, Statement on behalf of the Non-Aligned Movement (NAM) states-parties to the NPT, May 3, 2010, https://www.un.org/en/conf/npt/2010/statements/pdf/nam_en.pdf.

15. Javad Zarif, Statement before the 2015 NPT Review Conference on behalf of the NAM states-parties to the NPT, April 27, 2015, p. 3, https://www.reachingcriticalwill.org/images/documents/Disarmament-fora/npt/revcon2015/statements/27April_NAM.pdf.

16. 2020 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, "Nuclear Disarmament: Working Paper Submitted by Algeria," NPT/CONF.2020/WP.11, October 29, 2021.

17. Sylvia Mishra, “The Ukraine Crisis and the Global Nuclear Order,” Truman Center for National Policy, March 4, 2022, https://www.trumancenter.org/issues-posts/the-ukraine-crisis-and-the-global-nuclear-order.

18. “Annex: Stepping Stones for Advancing Nuclear Disarmament,” n.d., https://www.government.se/497342/globalassets/regeringen/lena-micko-test/stepping-stones-for-advancing-nuclear-disarmament.pdf.

19. Jeffrey W. Knopf, ed., Security Assurances and Non-Proliferation (Stanford: Stanford University Press, 2012), p. 9.

20. Peter Beerwerth, “CD Thematic Discussion on Negative Security Assurances (NSA)” (statement to the Conference on Disarmament, June 8, 2021), https://documents.unoda.org/wp-content/uploads/2021/06/20210608-Statement-DEU-for-web.pdf.

Francesca Giovannini is the executive director of the Project on Managing the Atom at the Belfer Center of the Harvard Kennedy School.