Reinforcing the Prohibition on Nuclear Explosive Testing and the CTBT
Joint NGO Statement* for the 2026 NPT Review Conference, May 1, 2026
For decades, a global ban on nuclear explosions has been a central goal and is now a central element of the nuclear nonproliferation and disarmament regime because an effective, comprehensive, verifiable test ban directly constrains the ability of all parties to develop new or more-advanced nuclear weapons.
The push to end all nuclear test explosions has also been driven by the widespread human suffering and environmental contamination produced by more than 2,000 atmospheric and underground nuclear test explosions since 1945. Hundreds of thousands of people have died and millions more have suffered— and continue to suffer—from illnesses directly related to the radioactive fallout from past nuclear detonations in the southwestern and western United States, islands in the Pacific, in Australia, western China, Algeria, across Russia, across Kazakhstan, India, Pakistan, the DPRK, and elsewhere.
While the CTBT and the de facto global nuclear testing moratoria have helped to reduce health and environmental injury from further nuclear-weapons testing, the effects of these detonations are still taking their toll on impacted communities across the globe.
Universal compliance with "zero-yield" prohibition on nuclear explosions established by the 1996 Comprehensive Test Ban Treaty is essential to the future of the NPT and global peace and security.
In the negotiations for the 1968 Treaty on the Non-Proliferation of Nuclear Weapons (NPT), a comprehensive test-ban was widely recognized as a critical part of the nuclear-weapon states’ obligation to meet their NPT Article VI commitment to “effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament.”
The preamble of the NPT specifically cites the goal of “the discontinuance of all test explosions of nuclear weapons for all time and to continue negotiations to this end.” And in 1995, NPT states parties agreed to indefinitely extend the treaty on the basis of the commitment to complete multilateral negotiations on the CTBT by 1996.
Not only did NPT states parties reaffirm their commitment to the CTBT at the 2000 and 2010 Review Conferences, but international support for the CTBT has been reaffirmed over the years through multiple UN General Assembly resolutions and UN Security Council (UNSC) resolutions.
UNSC resolution 1887 (2009) calls upon all states “to refrain from conducting a nuclear test explosion and to sign and ratify the Comprehensive Nuclear Test-Ban Treaty, thereby bringing the treaty into force at an early date.”
On the occasion of the twentieth anniversary of the opening for signature of the CTBT in Sept. 2016, the UNSC adopted the first-ever, CTBT-specific resolution (UNSC 2310), which reaffirms the global norm against nuclear-weapon-test explosions, calls on the eight remaining states that must ratify for entry into force to do so, and urges all states to provide their full financial and technical support to the CTBTO. The resolution was formally co-sponsored by forty-two states, including Israel.
The UNSC 2310 test-ban resolution also formally recognizes the important September 15, 2016, statement from the permanent five members of the council expressing the view that any nuclear test explosion would “defeat the object or purpose of the treaty.” The statement gives public expression to the existing legal obligation of all CTBT signatories not to test a nuclear weapon, even before the treaty enters into force.
Three decades after the conclusion of the CTBT, the treaty has near universal support and has established a global norm against nuclear test explosions. The nuclear testing taboo contributes to both nuclear nonproliferation and disarmament. It impedes the development of new and more advanced nuclear warhead designs, which helps prevent dangerous nuclear competition and strengthens international security.
The New Dangers to the CTBT and the De Facto Global Nuclear Test Moratorium
But the CTBT and the de facto global nuclear test moratorium cannot be taken for granted.
It is well known that the treaty's entry into force has been delayed due to the failure of eight key states, including the United States and China, to ratify, and Russia’s cynical decision to “de-ratify” in 2023.
Even though all 187 signatories are legally bound to respect the object and purpose of the treaty, the full benefits of the treaty – including the option to order short-notice on-site inspections to investigate potential violations – cannot be realized until it enters into force.
Additionally, the CTBT and the global nuclear test moratorium are now facing unprecedented new challenges related to:
- concerns about ongoing activities at former Russian, Chinese, and U.S. nuclear test sites
- U.S. accusations of noncompliance against China and Russia, and
- threats by the United States to conduct technically unnecessary, retaliatory nuclear test explosions "on an equal basis."
The situation requires a common-sense and unanimous response from all NPT states parties at this conference to:
- reaffirm their support for the global nuclear test moratorium established by the CTBT
- call for overdue action to secure the ratifications necessary for entry into force, and
- call upon the nuclear weapon states to promptly engage in professional, technical talks to devise voluntary confidence building measures that can be deployed before entry into force to ensure any activities at former nuclear test sites fully comply with the CTBT's Article I prohibition on nuclear test explosions.
Article I is recognized by all of the major negotiating parties to mean that supercritical nuclear tests (which produce a self-sustaining fission chain reaction) are banned, but subcritical experiments involving fissionable nuclear material (which do not produce a self-sustaining fission chain reaction) are permitted.
To this day, the United States, China, and Russia (unlike France) all continue to actively engage in weapons-related activities at their former nuclear testing sites. Each of the three also maintain “test readiness” programs to enable them to resume nuclear explosive testing if they were to decide to abandon the CTBT and the global moratorium on nuclear explosive testing.
Although the CTBTO’s International Monitoring System is operational and far more effective than originally envisioned, very low-yield nuclear test explosions can still be difficult to detect without on-site monitoring equipment or the option to trigger short-notice on-site inspections, which the CTBTO will only be able to conduct once the Treaty enters into force.
In 2023, the head of the U.S. National Nuclear Security Administration, Jill Hruby proposed a commonsense solution to address this challenge. She suggested the United States, Russia, and China could work together and 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."
In the absence of the CTBT’s entry into force or new voluntary confidence-building measures, there remains a risk that certain activities at these former nuclear testing sites that are prohibited -- nuclear experiments that produce a self-sustaining nuclear chain reaction -- might go undetected.
It is also possible that activities at former test sites or at other locations might be mistaken for a clandestine, very low yield nuclear test explosion, which might prompt another state to openly resume nuclear explosive testing.
This is the dangerous situation we are now facing.
Threats of Renewed Testing and Accusations of Noncompliance
On November 2, 2023, Russia cynically revoked its ratification of the CTBT, putting Russia on the same legal footing as the United States, which has yet to ratify the treaty. Russian President Vladimir Putin had previously stated that Moscow would not resume testing unless the United States did so first.
Opensource reports about construction activities at the former Chinese test site Lop Nor have raised concerns about Beijing increasing its readiness to resume nuclear weapon tests.
On October 30, 2025, U.S. President Donald Trump, threatened to resume U.S. nuclear testing "on an equal basis."
Since Trump’s initial nuclear testing comments, the White House has not been able to clarify what kind of nuclear tests Trump is talking about, and it has not offered any technical basis for his order to resume nuclear testing. The only reason appears to be political retribution: that he believes some other nuclear-armed states were testing their nuclear weapons.
Shortly after Trump initial comments, U.S. Secretary of Energy, Christopher Wright, suggested in an interview that Trump was referring to “non-critical tests” of nuclear weapons systems, probably a reference to subcritical nuclear experiments that are conducted at the Nevada National Security Site that do not involve a nuclear explosion due to a self-sustaining chain reaction. That interpretation has not yet been confirmed by the White House.
There is no technical, military, or political reason for the United States or any other nuclear weapon state to resume nuclear explosive testing. As Brandon Williams, the head of the National Nuclear Security Administration said during in a 2025 Congressional hearing: “we collected more [nuclear test] data than anyone else. And it is precisely that data that has underpinned our scientific basis for confirming the stockpile. I would not advise … testing.”
On February 6, senior U.S. officials alleged at the Conference on Disarmament that China conducted a nuclear test explosion on June 22, 2020. They also claimed that seismic data from one of the CTBTO primary seismic stations in Kazakhstan shows that China conducted a nuclear test explosion. On Feb. 17, U.S. Assistant Secretary of State Christopher Yeaw said the seismic magnitude was 2.75 and he claimed that it was produced by a 10-ton (TNT equivalent) explosion.
However, the data available from the IMS and other seismic monitoring stations in the region for that date do not indicate conclusively the seismic event was produced by a nuclear explosion, according to experts at the CTBTO and respected nongovernmental and scientific institutions.
On Feb. 6 and on Feb. 17, the CTBTO's Executive Secretary Robert Floyd issued a statement reporting that there had been two seismic events 12 seconds apart near China’s Lop Nor test site at 9:18 GMT on June 22, 2020, but that the strength of the signals was so low that “it is not possible to assess the cause of these events with confidence.”
He also reported that the CTBTO seismic station (PS23) at Makanchi, Kazakhstan suggested the locations of the June 22, 2020, seismic events were more than 100 kilometers away from the Lop Nur complex where China conducted nuclear tests in the past.
Floyd also noted the monitoring system “is capable of detecting nuclear test explosions with a yield equivalent to or greater than approximately 500 [tons] of TNT. These two events were far below that level. As a result, with this data alone, it is not possible to assess the cause of these events with confidence.”
“Mechanisms which could address smaller explosions are provided by the Treaty but can only be used once the Comprehensive Nuclear-Test-Ban Treaty enters into force. That is why it is important that the nuclear arms control framework includes the entry into force of the CTBT. The need is more urgent now than ever,” Floyd wrote. “Any nuclear test explosion, by any state, is of deepest concern,” he added.
On February 19, NORSAR, the Norwegian seismological institute, announced that it had surveyed data from seismic stations able to detect small seismic events near Lop Nor and had found only one candidate event on June 22, 2020. It estimated a seismic magnitude of 2.5-3.0, consistent with the U.S. claim.
But the NORSAR seismologists also stated: "The signal shows relatively strong compressional (P) waves compared to shear (S) waves, a feature that can be consistent with explosive sources. However, this characteristic alone is not diagnostic. Natural earthquakes can produce similar patterns, particularly when observations are limited to a single high-quality station … the data do not rule out that the event could have been a small natural earthquake…."
Similar allegations by the U.S. have also been raised towards Russia. In June 2019, during the first Trump administration, the U.S. Defense Intelligence Agency "assessed that Russia has conducted nuclear weapons tests that have created nuclear yield [in contrast] to the ‘zero yield’ nuclear weapons testing moratorium adhered to by the United States, the United Kingdom, and France.” The accusations have never specified when the alleged Russian activities may have occurred.
China and Russia have both denied the U.S. allegations.
We urge the relevant states to seek to clarify and resolve the matter in a professional manner in accordance with Article VI.C of the Comprehensive Test Ban Treaty, which provides that state parties “should, whenever possible, make every effort to clarify and resolve, among themselves or with or through the Organization, any matter which may cause concern about possible non-compliance with the basic obligations of this Treaty.”
It is important to recognize that allegations of clandestine nuclear testing absent independently verifiable data indicating a violation has occurred may be difficult to resolve.
Therefore, it is in the interest of all states not only to maintain the global moratorium on nuclear testing and advance toward CTBT entry into force, but also to develop and deploy additional tools to verify compliance prior to entry into force.
Two Nuclear Wrongs Would Not Make A Right
U.S. Assistant Secretary of State Christopher Yeaw stated on Feb. 23, that he hoped the U.S. allegations would “spur a discussion on how we all approach responsible nuclear testing behavior going forward.”
Civil society calls on every nation at this conference to make it clear that the only "responsible" nuclear testing behavior is not to do it.
Even if officials from the United States government or other governments believe that China conducted a clandestine nuclear test explosion in June 2020, or that Russia may have conducted such a test some time after 1996, two nuclear wrongs don't make a right.
Any resumption of nuclear explosive testing by China, Russia, the United States, or others would violate the "zero-yield" prohibition on nuclear test explosions established by the 1996 Comprehensive Test Ban Treaty. It would set off a chain reaction of nuclear testing worldwide that could blow apart the global nonproliferation system.
Any resumption of nuclear explosive testing would also risk producing new human suffering and environmental destruction and dishonor the longstanding struggles by impacted communities to address the ongoing, adverse health, social, environmental, and enduring consequences of these detonations and to put an end to nuclear weapons explosions once and for all.
Some U.S. officials may tell you that they think possible Chinese or Russian clandestine nuclear testing puts the United States at some kind of "intolerable disadvantage.”
This is hyperbole. The reality is that any decision to renew U.S. nuclear testing for the first time since 1992 would be militarily and technically unnecessary. Resuming U.S. nuclear explosive testing "on an equal basis" would only be an empty and counterproductive political reaction with far reaching consequences.
The U.S. nuclear weapons labs have confirmed year after year that there is no technical or military reason for the U.S. to resume testing.
On March 26, Richard Corell, the Navy admiral who commands U.S. nuclear forces, endorsed a finding by the Energy Department and Pentagon that the U.S. nuclear arsenal is safe and reliable and there is no need to conduct nuclear warhead tests. Noting that the Energy Department and Pentagon annually certify the safety and reliability of the U.S. nuclear arsenal, he expressed support for the most recent certification, which was issued for 2025-2026.
The United States, which has conducted some 1,054 nuclear test explosions since 1945, would learn little or nothing from additional low-yield nuclear test explosions. The same is true for Russia, which has conducted 715 nuclear tests.
According to the exhaustive 2012 study by the U.S. National Academy of Sciences on CTBT technical issues, these states “… are unlikely to be able to deploy new types of strategic nuclear weapons that fall outside the design range of their nuclear-explosion test experience without several multi-kiloton tests. Such multi-kiloton tests would likely be detectable (even with evasion measures) by appropriately resourced … national technical means and a completed IMS network.”
Conclusions
Any nuclear test explosion by any state for any reason would be a grave mistake.
We must keep the door to nuclear testing closed to preserve international peace and security, the CTBT, and the NPT.
This conference represents a critical opportunity for responsible states to rejuvenate efforts achieve entry into force of the CTBT and actively resist any move to resume nuclear testing, at any yield, for any reason, by any state.
- We call on all NPT states parties at this conference to reiterate their collective commitment to the cessation of all nuclear-weapon-test explosions or any other nuclear explosions.
- We call on the Conference to urge the five nuclear-armed NPT states to immediately commence technical consultations on joint mechanisms to develop new confidence building measures that strengthen capabilities to detect and deter prohibited nuclear testing prior to entry into force of the CTBT.
- We call upon the remaining Annex 2 states to immediately commence work to achieve their ratification of the treaty.
- We also call on all NPT states parties to acknowledge the humanitarian and environmental consequences of nuclear weapons testing and the vital importance of assisting communities affected by nuclear weapons use and testing. We call on all governments, particularly those responsible for conducting nuclear explosions in the past, to provide the necessary financial and technical support for long term environmental remediation programs, to expand access to health care especially as it relates to treatment of illnesses associated with radiation exposure, and to build independent capacity to monitor, assess, and address the environmental and health needs of the affected communities in the years to come.
Thank you for your attention.
Daryl G. Kimball, Executive Director, Arms Control Association
Mohamed AL SHAMI and Ahlam Lamrani, Alliance Internationale pour la Défense des Droits et des Libertés (AIDL)
Peter Wilk, Administrative Chair, Back from the Brink Coalition
Bruce J. Stedman, Back from the Brink Western Mass Hub
Ellen E Barfield, Co-founder and Coordinator, Baltimore, Maryland USA Chapter Veterans For Peace
Marie-Claire Graf, Co-President, Basel Peace Office*
Andreas Nidecker, Prof. (em.) Dr. med. Radiology, M.D., Basel Peace Office Switzerland*
Oliver Meier, Head Nuclear and Multilateral Disarmament, European Leadership Network*
Joseph C. Gerson, President, Campaign for Peace, Disarmament and Common Security
Togzhan Kassenova, Senior Fellow, Center for Policy Research, University at Albany*
Paul G. Richards, Mellon Professor of the Natural Sciences emeritus, Columbia University*
Rachel MacNair, Vice President, Consistent Life Network
John Tierney, Executive Director, Council for a Livable World
Hans M. Kristensen, Director Nuclear Information Project, Federation of American Scientists
Thomas Greminger, Ambassador, Geneva Centre for Security Policy (GCSP)*
Steve Baggarly, Member, Hampton Roads Campaign to Abolish Nuclear Weapons
Julien de Troullioud de Lanversin, Assistant Professor, Hong Kong University of Science and Technology (HKUST)*
Jean-Marie Collin, Director, ICAN France
Sean Conner, Executive Director, International Peace Bureau (IPB)
Michael Christ, Executive Director, International Physicians for the Prevention of Nuclear War
Hideo, ASANO Coordinator, Japan Campaign to Abolish Nuclear Weapons
Yerdaulet Rakhmatulla, Founder & CEO, JASA (Social Venture)*
David Cortright, Professor Emeritus, Kroc Institute for International Peace Studies, University of Notre Dame*
Deepshikha Kumari Vijh, Executive Director, Lawyers Committee on Nuclear Policy
Susan Mirsky, Chair, Nuclear Disarmament Working Group MAPA
Benetick Kabua Maddison, Executive Director, Marshallese Educational Initiative
Thomas Countryman, former U.S. Assistant Secretary of State for International Security and Nonproliferation
Susan F. Burk, Former Special Representative of the President for Nuclear Nonproliferation
Tariq Rauf, Former Head of Verification and Security Policy, Alternate Head of NPT Delegation, International Atomic Energy Agency*
Aaron Tovish, Senior Advisor, NoFirstUse.Global*
Irma Argūello, Founder & Chair, NPSGLOBAL Foundation
Patricia Marida, Coordinator, Ohio Nuclear Free Network
Charlene Howard, Executive Director, Pax Christi USA
Margaret Engel, Director of Policy and Outreach, Peace Action New York State
Akira Kawasaki, Executive Committee Member, Peace Boat
Meg Wade, Executive Director, Peace House, Ashland, OR
Paul George, Director, Peninsula Peace and Justice Center
John Hallam, Nuclear Disarmament Campaigner, People for Nuclear Disarmament*
Magritte Gordaneer, Director, Physicians for Social Responsibility
Marj Plumb, DrPH, Executive Director, Physicians for Social Responsibility Maine and Texas
Victor Mizin, Leading Research Fellow, Primakov IMEMO Institute, Russia Academy of Sciences*
Lucy Duff, Member, Prince George's County MD Peace Action*
Frank N. von Hippel, Professor of Public and International Affairs emeritus, Princeton University*
Dr. Dimity Hawkins, Program Coordinator, Nuclear Truth Project
Lauren Pope, Executive Director, Rehumanize International
Emma Claire Foley, Campaign Director, Defuse Nuclear War, RootsAction
Paul Meyer, Adjunct Professor of International Studies, Simon Fraser University and former Canadian Ambassador for Disarmament*
Tara Drozdenko, Director of Global Security Program, Union of Concerned Scientists
Frederick K. Lamb, Research Professor of Physics and Astronomy, University of Illinois*
*Affiliation for identification purposes only
**This statement was drafted and coordinated by the Arms Control Association and the European Leadership Network