"Though we have acheived progress, our work is not over. That is why I support the mission of the Arms Control Association. It is, quite simply, the most effective and important organization working in the field today." 

– Larry Weiler
Former U.S.-Russian arms control negotiator
August 7, 2018
The Enduring Value of the Comprehensive Test Ban Treaty and Prospects for Its Entry Into Force

By Daryl G. Kimball, Executive Director(1)

Presentation Delivered at the Ettore Majorana Centre, Erice, Sicily
August 22, 2008

"The one major area ... where the end is in sight, yet where a fresh start is badly needed, is in a treaty to outlaw nuclear tests. The conclusion of such a treaty, so near and yet so far, would check the spiraling arms race in one of its most dangerous areas. It would place the nuclear powers in a position to deal more effectively with one of the greatest hazards which man faces ... the further spread of nuclear arms. It would increase our security. It would decrease the prospects of war. Surely this goal is sufficiently important to require our steady pursuit ...."

-- President John F. Kennedy, June 10, 1963

The history of the nuclear age makes it clear that opportunities to reduce the risks posed by nuclear weapons are often very fleeting. When the right political conditions are in place, governmental leaders must seize the chance to make progress.

In 1958 and again in 1963, U.S. and Soviet leaders attempted to negotiate a comprehensive ban on all nuclear test explosions. They came close but failed to seal the deal. While the latter effort led to the 1963 Partial Test Ban Treaty, it took another three decades of on-and-off efforts to conclude negotiations on a comprehensive test ban treaty. During that time, hundreds more underground tests propelled further arms racing and proliferation.

Today, the 1996 Comprehensive Nuclear-Test-Ban Treaty (CTBT) remains a vital disarmament and nonproliferation instrument. By prohibiting all nuclear test explosions it impedes the ability of states possessing nuclear weapons to field new and more deadly types of warheads, while also helping to prevent the emergence of new nuclear-armed states.

Moving forward quickly on the CTBT is also an essential step towards restoring confidence in the beleaguered Nuclear Nonproliferation Treaty (NPT) regime. The nuclear-weapon states’ commitment to achieve the CTBT was a crucial part of the bargain that won the indefinite extension of the NPT in 1995 and the 2000 NPT Review Conference document.

U.S. Senate’s Untimely Rejection of the CTBT in 1999

Over the years, the importance of the Treaty to global security has only increased and international support has grown. Today, 179 countries have signed the CTBT, and 144 countries have ratified. Unfortunately, the U.S. Senate’s brief debate and untimely rejection of the CTBT in October 1999, coupled with the George W. Bush administration’s opposition to the Treaty, has slowed the momentum. Nine key states must still ratify to achieve entry into force.

Partially in response to U.S policy on the CTBT, some countries that have signed the CTBT, such as China and Israel, have delayed their ratification processes. Others, including India and Pakistan, have yet to sign the Treaty and are unlikely to do so unless the United States, China, and perhaps other hold-outs, finally ratify.

The situation is self-defeating and counterproductive. Given the U.S. signature of the CTBT and its test moratorium policy, the United States bears most CTBT-related responsibilities. Yet Washington’s failure to ratify has diminished its ability to prod other nations to join the Treaty and refrain from testing. At the same time, there is no need—nor is there any political support—for renewed U.S. testing for new nuclear warheads or for any other reason.

CTBT Helps Prevent Regional Conflicts and Avert Nuclear Arms Race

The CTBT is also needed to help head-off and deescalate regional tensions. With no shortage of conflict and hostility in the Middle East, ratification by Israel, Egypt, and Iran would reduce nuclear weapons-related security concerns and bring those states further into the nuclear nonproliferation mainstream. Action by Israel to ratify could put pressure on other states in the regions to do so. Iranian ratification would help address concerns that its nuclear program could be used to develop and deploy deliverable nuclear warheads.

Likewise, North Korean accession to the CTBT would help demonstrate the seriousness of its commitment to verifiably dismantle its nuclear weapons program through the Six-Party process. The ongoing India-Pakistan nuclear arms race could be substantially slowed to the benefit of both countries if they signed and ratified the CTBT or agreed to an equivalent legal instrument.

The CTBT would help limit the nuclear-weapons development capabilities of the established nuclear-weapon states. For instance, in the absence of a permanent CTBT:

  • China and Russia might test in order to make certain refinements in their nuclear arsenals. With further nuclear testing China might be able to reduce the size and weight of its nuclear warheads, which would make it easier for China to expand and add multiple independently targetable re-entry vehicles (MIRV) to its strategic arsenal if it wanted to do so. This could dramatically increase the number of nuclear warheads China could deliver; and
  • India and Pakistan could use further testing to perfect boosted fission weapons and thermonuclear warhead designs, greatly increasing the destructive power of their arsenals.

The global norm against testing remains strong, for now. Yet the absence of CTBT entry into force also means that the full range of verification and monitoring tools, confidence building measures, and the option of on-site inspections, are not available to help strengthen the international community’s ability to detect, deter, and if necessary respond to possible nuclear testing.

Moving forward – Prospects for CTBT Entry Into Force

To begin to break the ratification logjam and pave the way for entry into force, leaders in key states must make the right choices in three key areas.

First, it is essential that the next occupant of the White House builds upon growing bipartisan calls for U.S. reconsideration of the CTBT and initiates a serious effort to engage the new Senate on the issue with the goal of winning two-thirds support for ratification by the end of 2010. This is a difficult – but attainable – task requiring favorable political conditions, strong presidential leadership, and a well-executed ratification campaign.

Today, of course, these conditions do not all exist but the prospects and pressure for U.S. action on the CTBT are increasing. A growing array of Republican and Democratic national security opinion-leaders recognize the value of the CTBT and are calling for its reconsideration. (2)

In addition, the presumptive Republican and Democratic nominees for the presidency have, to varying degrees, expressed their support for reconsideration of the CTBT. On May 27, 2008, the presumptive Republican nominee, Senator John McCain, delivered a speech on “nuclear security” in which he said:

“As president I will pledge to continue America’s current moratorium on testing, but also begin a dialogue with our allies, and with the U.S. Senate, to identify ways we can move forward to limit testing in a verifiable manner that does not undermine the security or viability of our nuclear deterrent. This would include taking another look at the Comprehensive Test Ban Treaty…”

Whether McCain is interested in some new initiative to “limit testing in a verifiable manner” or will eventually find a way to endorse the CTBT itself is not clear at this point.

The presumptive Democratic nominee for president, Senator Barack Obama (Ill.) is on record in support of U.S. ratification of the CTBT. Obama said in a major foreign policy speech on 16 July 2008 that:

“…we’ll work with the Senate to ratify the Comprehensive Test Ban Treaty and then seek its earliest possible entry into force.”

Whoever wins can at least be expected to take a fresh and early look at the CTBT – and perhaps do much more.

Implementing a Bipartisan Process to Achieve Ratification

Translating pro-CTBT statements into winning over skeptical Senators and amassing a two-thirds majority in favor of ratification will take strong leadership and the commitment of significant political capital.

One factor working in favor of a successful second CTBT ratification campaign is the fact that the current and future U.S. Senate is somewhat different from the one that rejected the CTBT in 1999. The number of new Senators is significant because it means that many who voted against the CTBT are no longer in office.

Nevertheless, Senators will need to be briefed on the issue and their questions and concerns addressed thoroughly, respectfully, and consistently.

If the new U.S. president is fully committed to the CTBT, he should consider appoint a special, senior CTBT coordinator, backed with substantial interagency support and resources, who is solely focused on winning necessary support in the Senate. The administration will have to map out a step-by-step process for laying out the case for why the treaty is in U.S. national security interests through public speeches, expert reports, and hearings on Capitol Hill.

An administration seeking Senate support for the CTBT will likely find it necessary at some point to offer or consider understandings and/or conditions that help address the concerns of some senators who might not otherwise support the CTBT. Conditions that contradict the definitions and requirements of the Treaty or that undermine support for the CTBT by other states should be avoided. Under no circumstances should such end-game bargaining be initiated early in the process of winning the Senate’s support.

A well-prepared ratification effort will have to focus on delivering more persuasive answers on key issues that were at the center of the 1999 debate, particularly:

  • verification of the zero-yield CTBT; and
  • the maintenance of the U.S. stockpile in the absence of testing.

On verification, the 2002 National Academy of Sciences report stated:

“The capabilities to detect and identify nuclear explosions without special efforts at evasion are considerably better than the “one kiloton worldwide” characterization that has often been stated for the IMS. If deemed necessary, these capabilities could be further improved by increasing the number of stations in networks whose data streams are continuously searched for signals. Underground explosions can be reliably detected and can be identified as explosions, using IMS data, down to a yield of 0.1 kt (100 tons) in hard rock if conducted anywhere in Europe, Asia, North Africa, and North America. In some locations of interest such as Novaya Zemlya, this capability extends down to 0.01 kt (10 tons) or less.”

Since the 1999 Senate vote and the 2002 National Academy of Sciences report, the International Monitoring System has only grown in size and sophistication. For example, more than 10 of the IMS primary seismic stations detected the ground tremors produced by the relatively small yield, Oct. 9, 2006 North Korean underground nuclear test explosion near P’unggye, according to the January 2007 newsletter of the CTBTO, Spectrum. The North Korean test blast was estimated by various national, international, and scientific monitors to be less than 1 kiloton (TNT equivalent) in yield.

More significantly, one of 10 experimental “noble gas” monitoring stations that are to be part of the IMS detected trace amounts of unique radioactive material that confirmed the explosion was nuclear. The station, which is located near Yellowknife in Canada’s Northwest Territories, detected two spikes in xenon gas readings, on Oct. 22 and 25, which, on the basis of atmospheric modeling, were consistent with the North Korean test.

When the combination of existing national means of intelligence, as well as world’s network of tens of thousands of civilian seismic monitoring stations, plus the option of on-site inspections are taken into account, no would-be cheater could conduct a nuclear weapon test explosion in underground, underwater, or in the atmosphere without a very high risk of detection.

The other key issue is whether the United States can continue to rely on its stockpile stewardship program to maintain its arsenal under a permanent CTBT? The short answer is: yes.

As the U.S. National Academy of Sciences reported in July 2002, the United States "has the technical capabilities to maintain confidence in the safety and reliability of its existing nuclear-weapon stockpile under [a test ban], provided that adequate resources are made available to the Department of Energy's nuclear-weapons complex and are properly focused on this task."

Though the Energy Department has determined each year for the last decade that the U.S. nuclear arsenal remains safe and reliable without nuclear testing, some claim—as they did in 1999—that as time goes on there may be age-related problems in the nuclear stockpile. (3)

The good news is that all of the technical evidence available shows that such concerns are greatly overstated. New government studies on plutonium longevity completed in 2006 have found that the plutonium primaries of most U.S. nuclear weapons have a minimum lifetime of 85 years, which is twice as long as previous estimates.

According to the National Academy panel, which included three former lab directors, age-related defects mainly related to non-nuclear components can be expected, but nuclear test explosions “are not needed to discover these problems and is not likely to be needed to address them.”

Rather, the panel says, the key to the stewardship of the arsenal is a rigorous stockpile surveillance program, the ability to remanufacture nuclear components to original specifications, minimizing changes to existing warheads, and non-explosive testing and repair of non-nuclear components.

Thomas D’Agostino, acting National Nuclear Security Administration (NNSA) administrator said in March 2007 that “stockpile stewardship is working. This program has proven its ability to successfully sustain the safety, security and reliability of the stockpile without the need to conduct an underground test for well over a decade.”

Nevertheless, the Bush administration has initiated a new and poorly defined program to design and build new warheads to “replace” certain warhead types already in the arsenal. A chief selling point for the so-called Reliable Replacement Warhead (RRW) program is unsubstantiated assertion that the current approach to stockpile stewardship is unsustainable and unreliable and that RRW will reduce the likelihood that the United States will need to resume testing. The Department of Energy said in 2005 that the goal of the RRW program is to produce a small quantity of new replacement warheads by 2012-2015 for the W-76 warhead.

The W-76 was originally designed to minimize size and weight and maximize the explosive yield. According to a small minority of U.S. nuclear weapons scientists, this might make its nuclear components more sensitive to aging effects. In theory, the RRW is supposed to increase design margins (by using more fissile material) to maximize reliability.

But rather than build new replacement warheads at great cost, the United States could increase confidence in certain warheads by other methods, such as adding more boost gas to increase the explosive energy of the primary stage of the weapon well above the minimum needed to ignite the secondary or main stage.

NNSA officials also argue they can build replacement warheads without nuclear explosive proof testing. However, a recent report by an independent group of nuclear weapons scientists known as JASON found that it is by no means certain that the proposed RRW design can be validated as “reliable.” While many legislators have their doubts, some believe that if the new warheads are indeed more reliable, then test ban skeptics in the Senate should be more willing to support CTBT ratification.

It is doubtful that new warheads would be enough to convince the skeptics and may be more risky for the CTBT. Given that the new replacement warheads are years and billions of dollars away from reality, many CTBT skeptics might argue, as they did in 1999, that it is too early to tell whether the new warheads will work reliably and without proof testing. Furthermore, if Congress once again acts to cut or eliminate the Bush administration’s request for funding the RRW program (which is highly likely), RRW may be a non-factor in any future discussion about the CTBT.

It is also important to consider the fact that building a new generation of nuclear weapons to win support for a global test ban is contrary to the spirit of the CTBT, a chief aim of which is to end qualitative nuclear arms competition.

2. High-Level Diplomatic Pressure Must Continue on “Hold-Out” States

Not only must the next U.S. president and Senate act favorably on the CTBT, but the leaders of states committed to the CTBT must exercise much more consistent, top-level diplomacy in support of entry into force. The numerous statements by individual governments and regional groupings of states are essential but are not sufficient. Too often, they fail to press their counterparts in the nine CTBT hold-out states.

One important opportunity will arrive this September when foreign ministers from CTBT ratifying states will gather to issue their biennial joint statement calling for the Treaty’s entry into force. Another is the next Conference on Facilitating the Entry into Force of the CTBT, likely to take place in the fall of 2009, to help prod the U.S. president and other hold-outs to approve the Treaty.

China merits special attention. For years, Beijing has reported that the Treaty is before the National People’s Congress for consideration but has apparently taken no action to win legislative approval.

3. The Test Ban and Civil Nuclear Trade with India

There is another equally important test of leadership on the CTBT: this week’s Nuclear Suppliers Group (NSG) debate on the Bush administration proposal for an India-specific exemption from NSG guidelines that restrict trade with states that do not accept full-scope safeguards. The United States’ August 6 proposal to exempt India from NSG rules should be rejected, in part because it establishes no meaningful response or mechanism if India tests again.(4)

It would be highly irresponsible for CTBT signatories in the NSG not to establish CTBT signature as a condition of nuclear trade. If, as Prime Minister Manmohan Singh said in July 2005, India is prepared to take on the responsibilities expected of other advanced nuclear nations, it is reasonable to expect that India should agree to a legally-binding test moratorium, as the five original nuclear-weapon states have all done.

Incredibly, Indian officials also want terms of trade that would allow supplier states to provide India with a strategic fuel reserve that could be used to outlast any fuel supply cut off or sanctions that may be imposed if it resumes nuclear testing.

The U.S. proposal flatly contradicts provisions in the 2006 U.S. implementing legislation that define the terms of U.S. nuclear trade with India. If NSG supplier states do agree to supply fuel to India, they must avoid actions that might enable or encourage Indian nuclear testing. At the very least, they should establish that, if India were to resume nuclear testing, all NSG nuclear cooperation with India would be terminated immediately and unused fuel supplies from NSG states would be returned.


CTBT entry into force is within reach. With the 2008 U.S. election and the 2010 NPT Review Conference approaching, it is vital to redouble efforts to secure ratification by key CTBT hold-out states, accelerate work to complete the International Monitoring System, and avoid developments that would damage the CTBT regime. The next one to two years may represent the best opportunity to secure the future of this long-awaited and much-needed Treaty.

1. The Arms Control Association (ACA) is a non-governmental organization established in 1971 to promote public understanding of arms control issues and to advocate effective nuclear, biological, chemical, and conventional arms control solutions. ACA publishes the monthly journal, Arms Control Today. Daryl G. Kimball has served as ACA’s executive director since 2001. He previously served as security programs director for Physicians for Social Responsibility (1989-1997) where he helped lobby for the U.S. nuclear test moratorium legislation of 1992 and negotiation of a zero-yield CTBT. Kimball was executive director of the Coalition to Reduce Nuclear Dangers (1997-2001) where he led a group of NGOs in their efforts to win support for U.S. CTBT ratification.

2. “Toward a nuclear weapons free world,” George Shultz,  Henry Kissinger, William Perry, and Sam Nunn, The Wall Street Journal, Jan. 4, 2007.

3. “It’s because of the Stockpile Stewardship Program that I can stand before you today and tell you our current stockpile is reliable and safe today. So, what I fear most is not the reliability of the systems today.  I think they are reliable today.  I sense there’s a cliff out there some place and I don’t know how close I am to the edge of that cliff,” Gen. Henry Chilton, Commander of U.S. Strategic Command, in a speech in Washington, D.C., July 22, 2008.

4. See “U.S. Proposal for India-Specific Exemption to Nuclear Supplier Group Guidelines Circulated August 2008,” an Arms Control Association Note for Reporters by Daryl G. Kimball < http://www.armscontrol.org/node/3274>.