Twenty years ago this month, the Berlin Wall came down, hastening the end of the Cold War. Less than three years later, Moscow and Washington agreed to halt nuclear testing. In 1996, after more than 2,000 nuclear test explosions, the world’s nations concluded the Comprehensive Nuclear Test Ban Treaty (CTBT) in order to curb the spread of nuclear weapons and prevent the renewal of superpower nuclear arms competition.

Today, there is no technical or military reason to resume U.S. nuclear weapons testing, and it is in the national security interest to help prevent nuclear weapons testing by others. A growing list of bipartisan leaders agree that by ratifying the CTBT, the U.S. stands to gain an important constraint on the ability of other states to build new and more deadly nuclear weapons that could pose a threat to American security. As Sigfried Hecker, former director of Los Alamos National Laboratory, recently put it: “the single most important reason to ratify the CTBT is to stop other countries from improving their arsenals.”[1]

For example, a new round of nuclear weapon test explosions would allow China to perfect smaller warhead designs and allow it to put multiple warheads on its relatively small arsenal of strategic ballistic missiles—a move that could allow it to increase its nuclear strike capability. Without nuclear weapon test explosions, potential nuclear-armed states like Iran would not be able to proof test the more advanced, smaller nuclear warhead designs that are needed in order to deliver such weapons using ballistic missiles.

Since the CTBT was briefly considered by the U.S. Senate in 1999, there have been technical advances in the U.S. stockpile stewardship program and verification and monitoring capabilities that should address earlier concerns that led many Senators to vote “no.” President Obama and his cabinet have called for the reconsideration of the Treaty and pledged to work intensively with Senators so they are fully briefed on key technical and scientific developments and have updated intelligence assessments before the CTBT comes before the Senate sometime in 2010.

Unfortunately, some pro-testers are stuck in the past. In his October 20 Wall Street Journal op-ed, “Why We Need to Test Nuclear Weapons,” Senator Jon Kyl (R-Ariz.) relies on several old and misleading arguments against the CTBT.

Maintaining the Reliability of the U.S. Arsenal

For instance, Senator Kyl claims that “concerns over aging and reliability [of the U.S. arsenal] have only grown.” In fact, confidence in the ability to maintain U.S. warheads is increasing. Contrary to the assertions of CTBT critics, maintaining the reliability of proven U.S. nuclear warhead designs does not depend on a program of nuclear test explosions. Through the Stockpile Stewardship Program, which includes nuclear weapons surveillance and maintenance, non-nuclear and subcritical nuclear experiments, and increasingly sophisticated supercomputer modeling, each warhead type in the U.S. nuclear arsenal has been determined to be safe and reliable through a rigorous certification process each year since 1994.

A 2002 National Academy of Sciences panel, which included three former nuclear weapons lab directors, found that the current Stockpile Stewardship Program provides the technical capabilities that are necessary to maintain confidence in the safety and reliability of the existing seven types of nuclear warheads in the active stockpile, "provided that adequate resources are made available...and are properly focused on this task."[2]

Over the past decade, successful Life Extension Programs have refurbished and modernized major warhead types and, according to independent experts, can continue to do so indefinitely. Nuclear weapons laboratory studies completed in 2006 demonstrate that the plutonium cores of nuclear weapons are not affected by aging for at least 85 years. With a current average stockpile age of 25 years, existing plutonium parts may not need replacement for 60 years or more. Age-related defects in non-nuclear components can be expected, but nuclear testing is not needed to discover these problems and is not needed to address them.

The bottom line: the U.S. nuclear arsenal has and can be maintained effectively and reliably through non-nuclear tests and evaluations, combined with the remanufacture of key nuclear components to previous design specifications, if necessary.

Effective Verification

Despite a decade of advances in national and international monitoring capabilities, Senator Kyl is repeating an age-old charge that clandestine tests cannot be verified with absolute certainty. This argument misses the point on verification and implies that low-yield tests are worth the high risk of getting caught. Those countries that are best able to successfully conduct such clandestine testing already possess advanced nuclear weapons of a number of types and could add little, with additional testing, to the threats they already pose to the United States. Countries of lesser nuclear test experience and/or design sophistication would be unable to conceal tests in the numbers and yields required to master advanced warheads.

In other words, no would-be cheater could be confident that a nuclear explosion of sufficient yield to possibly threaten U.S. security would escape detection. To the extent that there are concerns about cheating, the United States’ capability to detect and deter possible clandestine nuclear testing by other states is substantial and growing. Those capabilities will only be even greater with the CTBT—its global verification and monitoring network and the option of short-notice on-site inspections—than without it. The CTBT provides for monitoring stations inside Russia, China, and other sensitive locations, including some places where we could not gain access on our own. By establishing a legally-binding ban on testing and data vetted by the international community, the CTBT gives the U.S. additional tools to resolve compliance concerns and address potential violations.[3]

On-Site Inspections

The CTBT would provide, for the first time, the option of short-notice inspections in response to signs of a suspicious event—an important deterrent against potential clandestine nuclear testing. The Treaty also permits information from national technical means of verification to support an on-site inspection request.

Senator Kyl, however, suggests that because the CTBT requires 30 of 51 nations on the Comprehensive Test Ban Treaty Organization’s (CTBTO) Executive Council to agree to an on-site inspection, states unfriendly to the U.S. could block such inspections. In reality, the CTBT’s on-site inspection provisions were established to balance the need for rapid response to a suspected test against the possibility of “frivolous or abusive” inspections. The approval of 30 out of 51 members of the Executive Council was designed to give nations like the U.S. and Israel the confidence that inspections would be approved as needed, but not by a small minority with questionable motives.

Senator Kyl also misleadingly claims that the CTBT allows a state suspected of testing to declare their test sites off-limits. In truth, to protect national security interests unrelated to the on-site inspection, states are allowed to restrict access to parts of the inspection area no larger than four square km or a total of no more than 50 square km. However, if an inspected state restricts access it must provide alternative ways for the inspection team to carry out its mission. If no allowances had been made for unrelated national security interests, one could imagine that Senator Kyl might complain such inspections would infringe on U.S. sovereignty.

North Korea has provided two recent real-world tests of U.S. and global monitoring capabilities. In October 2006, the international monitoring system easily detected North Korea’s relatively low-yield (0.6 kiloton) nuclear explosion at 22 seismic stations and had a solid estimate of its location within five hours of the event. Tell-tale radioactive gases from this test were detected by South Korea, the U.S., and 4,600 miles away in Yellowknife, Canada, at one of the international monitoring network’s noble gas monitoring stations.

The second test by North Korea on May 25, 2009, with a yield of a few kilotons, was detected by a total of 61 international seismic stations. Senator Kyl has tried to suggest that because the international monitoring network did not detect radionuclide particles from the second North Korean test explosion, the system failed.

But, in fact, the seismic evidence alone would have provided a firm basis for on-site inspections. The CTBT sets a limit of 1,000 square km for the inspected area, and the seismic data located the test well within this limit. According to the CTBTO, “The data would have provided a clear lead to the inspection team regarding where to look.”

Zero Means Zero

Another misleading charge from Senator Kyl and other pro-testers is the claim that because the CTBT does not define “nuclear test explosion,” some states such as Russia believe low-yield and “hydronuclear” tests are permitted. Wrong again. The record is clear: Article I of the CTBT bans “any nuclear weapon test explosion or any other nuclear explosion.”

In 1999, the U.S. CTBT negotiator Ambassador Stephen Ledogar testified before the Senate Foreign Relations Committee on the subject and said: "I have heard some critics of the Treaty seek to cast doubt on whether Russia, in the negotiation and signing of the Treaty, committed itself under treaty law to a truly comprehensive prohibition of any nuclear explosion, including an explosion/experiment/event of even the slightest nuclear yield. In other words, did Russia agree that hydronuclear experiments would be banned, and that hydrodynamic explosions (which have no yield because they do not reach criticality) would not be banned?”

Ledogar went on to say:“The answer is a categoric "yes." The Russians, as well as the other weapon states, did commit themselves. That answer is substantiated by the record of the negotiations at almost any level of technicality (and national security classification) that is desired and permitted. More importantly for the current debate, it is also substantiated by the public record of statements by high level Russian officials...”

As the Russian government explained to the Duma when it ratified the CTBT in 2000: “Qualitative modernization of nuclear weapons is only possible through full-scale and hydronuclear tests with the emission of fissile energy, the carrying out of which directly contradicts the CTBT.” It is clear to all parties that the CTBT establishes a “zero-yield” prohibition on nuclear test explosions.

The Test Ban and Nonproliferation

Ignoring years of evidence to the contrary, Senator Kyl also asserts that ratification of the CTBT has no relationship to the ability of the U.S. to strengthen efforts to curb the spread of nuclear weapons. Senator Kyl, who argued for continued nuclear testing in the 1990s, overlooks the fact that the Nuclear Non-Proliferation Treaty (NPT) would not likely have been renewed indefinitely in 1995 without the pledge from the U.S. and the other original nuclear powers to stop testing, support the CTBT, and conclude test ban negotiations by the end of 1996. If Washington fails to fulfill its commitment to join the CTBT, U.S. leverage to strengthen nuclear safeguards, tighten controls on nuclear weapons-related technology, and isolate states that don’t follow the nonproliferation rules will be weakened.

CTBT proponents do not claim that an end to U.S. testing or further superpower nuclear arms reductions would directly lead other states, such as Iran, to give up their nuclear ambitions. Such a direct link is overly simplistic.

As Ellen Tauscher, Under Secretary of State for Arms Control and International Security, said in a speech in Omaha on July 29, “We are not so naïve as to believe that problem states will end their proliferation programs if the U.S. and Russia reduce our nuclear arsenals. But we are confident that progress in this area will reinforce the central role of the NPT and help us build support to sanction or engage states on favorable terms to us. Our collective ability to bring the weight of international pressure against proliferators would be undermined by a lack of effort towards disarmament.”

Doing Nothing Is Unwise

Without action on the CTBT, the risks of a resumption of testing will only grow. Ratification of the CTBT by the U.S. would reinforce the taboo against testing and prompt other hold-outs—such as China, India, and Pakistan—to ratify or reconsider the Treaty.

The prospect of U.S. ratification has already led Indonesia’s Foreign Minister to pledge Jakarta’s support for ratification if the U.S. goes forward. It has also spurred fresh thinking in New Delhi. India’s National Security Advisor M. K. Narayanan said in an August 30 interview in The Hindu: “we are steadfast in our commitment to the moratorium.” Asked what India might do if the U.S. and China were to ratify, he said, “I think we need to now have a full-fledged discussion on the CTBT. We’ll cross that hurdle when we come to it.”

Nuclear testing is a dangerous and unnecessary vestige of the last century that the U.S. has already given up. The U.S. has not conducted a nuclear test since 1992 and the nuclear weapons labs do not need nuclear explosive testing to maintain the reliability of the U.S. nuclear deterrent. U.S. action on the CTBT would build support for updating and strengthening the global nonproliferation system at a critical juncture. The Senate’s reconsideration of the CTBT should be based on an honest and up-to-date analysis of the facts and the issues at stake.

Daryl G. Kimball is executive director of the Arms Control Association.


1. Jennifer Weeks, "Nuclear Disarmament: Will President Obama’s Efforts Make the U.S. Safer?" CQ Researcher, Vol. 19, No. 34, pp. 813-836.

2. "Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty," National Academy of Sciences, 2002.

3. " Findings and Recommendations Concerning the Comprehensive Test Ban Treaty," General John M. Shalikashvili (USA, Ret.), Special Advisor to the President and Secretary of State, January 2001.