The Washington, D.C.-based Arms Control Association (ACA) has issued an urgent call to action regarding President Trump’s intention to resume nuclear weapons testing. In support of this objective, I’m asking my US readers, as requested by the ACA, to contact their Senators and Representatives in support of legislation that would block a return to the technically unnecessary return to explosive testing of nuclear weapons. This type of testing has long been deemed unneeded by the US nuclear weapons laboratories since the UN opened the Comprehensive Test Ban Treaty for signature on September 24, 1996.1 Since that time, the US, Russia, the UK, France, and China continued to conduct sub-critical nuclear weapons tests. Such tests require less energy than a full fission-based chain reaction but are sufficient to validate the viability of a weapon's design.
But I have one critical distinction from the ACA: I believe we must preserve sub-critical testing that has continued since the signing of the Comprehensive Test Ban Treaty, together with important verification facts that need greater emphasis.
The Unconfirmed Accusation
On February 6, Under Secretary DiNanno accused China of conducting a secret nuclear test on June 22, 2020, without providing evidence that can be confirmed in support. This accusation has been seriously doubted by all independent monitoring authorities internationally. The idea that such tests can evade modern monitoring technology by using a method called decoupling, first proposed thirty years ago by RAND Physicist Albert Latter, has been disproved by American nuclear testing of the concept.2 The CTBTO’s Executive Secretary stated explicitly that the International Monitoring System detected no evidence of a nuclear explosion on that date.
This matters because modern monitoring capabilities—seismic networks, satellite surveillance, infrasound sensors, and radionuclide detection—are more than sufficient to detect yield-producing nuclear tests, even at very low yields. The comprehensive verification system built internationally over decades works. The absence of confirmation is not a monitoring failure; it indicates the alleged test did not occur.
Using an unsubstantiated six-year-old allegation to justify abandoning a 34-year moratorium is political maneuvering, not a substantive verification concern.
The Technical Distinction That Matters
The Comprehensive Test Ban Treaty (CTBT) prohibits all nuclear test explosions—meaning any test that produces nuclear yield. What it permits are subcritical experiments: zero-yield tests that use conventional explosives to study plutonium behavior without achieving a nuclear chain reaction.
This distinction is fundamental: We must oppose any yield-producing nuclear test, whether classified as low or full-scale underground detonations. Atmospheric, underwater, or space tests (already banned by the 1963 Partial Test Ban Treaty and highly detectable)
These violate the global moratorium, provide no technical benefit that cannot be achieved through other means, and would likely provide precedent for reciprocal testing by Russia and China, and provide the excuse for others, such as North Korea, to resume underground nuclear testing from which they’ve abstained for the past eight years. Moreover, modern monitoring makes clandestine testing extraordinarily difficult—underground tests require substantial preparations visible to satellites, and produce seismic signatures detectable globally even at low yields.
We must preserve: Subcritical (zero-yield) experiments, which are essential for maintaining stockpile confidence without explosive testing. These should continue—ideally with enhanced transparency through notification frameworks that build international confidence.3
Why This Distinction Matters Strategically
The current legislative proposals (RESTRAIN Act H.R. 5894, No Nuclear Testing Act S. 3090) aim to prevent funding for nuclear testing.4 This is vital. But we must ensure this prohibition targets only yield-producing tests, not the subcritical experiments that have successfully maintained our arsenal for 34 years.
The United States conducted 1,054 nuclear tests before the 1992 moratorium—more than the rest of the world combined. China conducted 45. This massive database gives American weapons designers an unmatched foundation. Resuming testing helps adversaries close this gap while providing the US with no technical benefit we cannot achieve through superior diagnostic capabilities, such as the Scorpius facility.
What You Can Do
For US readers: Contact your Senators and Representative. Support the legislation while urging them to:
Maintain the technical distinction between prohibited yield-producing tests and permitted subcritical experiments
Reject unsubstantiated allegations as justification for policy changes
Recognize that modern verification systems work—any testing would be detected
For international readers: Express concern to your own government about the global implications of resumed testing. The moratorium holds because all parties recognize that the alternative serves no one’s interests.
I’ve written to my Maryland Senators and Representative, with a supporting email to Representative Dina Titus (the House sponsor of the legislation) and Senator Markey, making these small but important technical distinctions explicit. The letter emphasizes that:
The assumed China test of five years ago lacks independent confirmation from the seismic monitoring and other verification
Modern monitoring is more than sufficient to detect tests going forward
Subcritical experiments must be distinguished from yield-producing tests
Atmospheric, space, and underwater tests are banned and highly detectable
Underground test preparations are especially vulnerable to satellite detection. To evade detection by “decoupling,” the test requires a large underground cavity in which the detonation is made. Tests in the United States during the Ploughshares program showed the method to be ineffective.
[LETTER TEMPLATE - COPY AND PASTE]
Use the letter below, personalize it with your details, and send it to your elected officials.
Subject: Support for RESTRAIN Act with Critical Technical Clarification
Dear Senator [Name] / Representative [Name],
I write to express my strong support for the RESTRAIN Act (H.R. 5894) and the No Nuclear Testing Act (S. 3090), which would prohibit funding for explosive nuclear weapons testing. However, I urge you to ensure that this critical legislation maintains a clear technical distinction between yield-producing tests—which must be prohibited—and subcritical experiments, which are essential for stockpile stewardship and should continue with enhanced transparency.
The Threat
President Trump’s October 30, 2025, declaration to resume nuclear testing “on an equal basis” and Under Secretary DiNanno’s February 6, 2026, accusation against China have created a genuine risk of ending the 34-year global moratorium on nuclear explosive testing. As I detail in my recent analysis, there is no technical justification for this policy. The Stockpile Stewardship Program has proven more successful than anticipated, and NNSA leadership has confirmed that no modernization requirement demands yield-producing tests.
The Unsubstantiated Accusation
The administration’s claim that China conducted a low-yield nuclear test on June 22, 2020, has not been confirmed by any independent monitoring authority. The CTBTO’s Executive Secretary stated explicitly that the International Monitoring System detected no evidence of a nuclear explosion on that date. Modern seismic networks, combined with satellite surveillance, infrasound sensors, and radionuclide detection, are more than sufficient to detect yield-producing tests—even at very low yields.
The absence of corroborating evidence is not a monitoring failure—it indicates the event did not occur. Using an unsubstantiated six-year-old allegation to justify abandoning a 34-year moratorium is not a verification concern; it is political theater.
The Critical Distinction
The Comprehensive Test Ban Treaty prohibits all nuclear test explosions—meaning any test that produces nuclear yield, regardless of magnitude. What the Treaty permits, and what the United States has successfully conducted since 1992, are subcritical experiments: tests using high explosives to study plutonium behavior without achieving a self-sustaining nuclear chain reaction. These experiments produce zero nuclear yield.
This distinction is not semantic—it is fundamental to maintaining both nuclear deterrence and nonproliferation:
Subcritical experiments (zero-yield):
Essential for certifying stockpile reliability without explosive testing
Conducted by all major nuclear powers within CTBT parameters
Provide confidence in aging warhead components
Enable validation of life extension programs
Should continue with enhanced transparency and prior notification
Yield-producing tests (any nuclear yield):
Violate the CTBT and global moratorium
Provide no technical benefit that the US cannot achieve through subcritical means
Are highly vulnerable to detection by modern monitoring systems and national as well as open source technical means of verification
Would trigger reciprocal testing by adversaries, thereby negating any specific advantage to be achieved by the test.
Give Russia and China opportunities to close the massive US data advantage
Undermine the nonproliferation regime at the April 2026 NPT Review Conference
The Verification Reality
Modern monitoring capabilities make clandestine nuclear testing extraordinarily difficult:
Underground tests require massive preparation activities easily visible to satellite surveillance, and produce seismic signatures detectable by the global monitoring network even at low yields
Atmospheric, space, and underwater tests are explicitly banned by the 1963 Partial Test Ban Treaty and are highly detectable through multiple monitoring methods
The CTBT International Monitoring System now includes 337 facilities worldwide using seismic, hydroacoustic, infrasound, and radionuclide detection capabilities that have improved by orders of magnitude since the 1990s
Claims that adversaries can conduct militarily significant tests while evading this comprehensive monitoring network are not supported by technical evidence. Any attempt to resume testing—by any nation—would be detected.
The Ambiguity Risk
Assistant Secretary Yeaw’s February 23 statement calling for “discussion on responsible nuclear testing behavior” is dangerously ambiguous. There is only one responsible position: no yield-producing nuclear tests by any nation. However, this prohibition must not extend to subcritical experiments, which should instead be conducted with greater transparency through established notification and consultation frameworks.
The current legislation must make this distinction explicit. We cannot allow political rhetoric about “equal basis” testing to blur the line between:
Legitimate zero-yield experiments are essential for stockpile confidence, and
Prohibited yield-producing tests that serve no technical purpose while accelerating arms competition
The Strategic Stakes
A US return to yield-producing testing would:
Collapse the 34-year global moratorium based on unsubstantiated allegations
Provide political cover for Russian, Chinese, and North Korean testing programs
Undermine US credibility at the April 2026 NPT Review Conference
Validate proliferation advocates’ claims that nuclear powers have abandoned Article VI commitments
Help adversaries close the massive US advantage in test data (1,054 US tests vs. 45 Chinese tests)
Demonstrate that comprehensive monitoring and verification can be ignored for political convenience
My Request
I urge you to:
Co-sponsor and support the RESTRAIN Act (H.R. 5894) and No Nuclear Testing Act (S. 3090)
Ensure the legislation clearly distinguishes between:
Prohibited: Any nuclear test producing yield (hydronuclear, low-yield, or full-scale), whether underground, atmospheric, underwater, or in space
Permitted: Subcritical experiments producing zero nuclear yield
Advocate for transparency frameworks that encourage prior notification and consultation for subcritical experiments, building confidence without constraining essential stockpile stewardship activities
Reject unsubstantiated allegations as justification for policy changes that undermine US security interests
Reject any “ambiguous” language about “responsible testing behavior” that could be interpreted to permit low-yield nuclear explosions
There is no technical case for yield-producing nuclear tests. The weapons laboratories confirm this. The scientific community confirms this. The monitoring systems work. The administration’s position serves political goals while undermining strategic interests and dismissing verification capabilities we spent decades developing.
Congress has the constitutional authority to prevent this dangerous policy through its appropriations power. I urge you to exercise that power decisively, while ensuring that legitimate subcritical experiments—conducted transparently within CTBT parameters—can continue to maintain confidence in our deterrent without opening the door to a renewed nuclear arms race.
The scientific community that built these weapons sees no technical case for yield-producing tests. The weapons laboratories confirm this. The monitoring systems we’ve built work. We must prevent political rhetoric from overriding technical judgment—while preserving the legitimate tools that maintain deterrence without explosive testing?”
Thank you for your attention to this critical matter.
Sincerely,
If this analysis is useful to you, the most effective thing you can do right now is share it with someone who has a stake in the outcome — a scientist, a policy professional, an engaged citizen, or anyone who should know what's actually at stake in this debate.
For a deeper examination of how we arrived at this moment — the dismantling of the arms control frameworks that defined nuclear security for half a century — my book:
The Last Treaty: Innovation, Nuclear Risk, and the End of Arms Control
is available free to Kindle Unlimited subscribers on Amazon.
Notes:
Understanding the Terms: Yield, Criticality, and Verification
The debate around nuclear testing turns on a set of technical distinctions that are often obscured by political language. Three concepts are essential to following this argument clearly.
Nuclear Yield and What “Low-Yield” Actually Means
Nuclear yield measures the explosive energy released by a nuclear detonation, expressed in kilotons (kt) or megatons (Mt) of TNT equivalent. Low-yield weapons are generally defined as devices producing 10 kilotons or less — though the term is sometimes stretched to 50 kilotons for tactical battlefield applications. The W76-2, the warhead the United States currently deploys on submarine-launched missiles, is estimated at 5 to 7 kilotons.
The phrase “low-yield” is dangerously misleading. A 6-kiloton device is approximately 500 times more powerful than the largest conventional bomb in the US arsenal. There is nothing small about it. The label exists to suggest limited, controllable use — which is precisely why arms control analysts have long argued it lowers the psychological threshold for nuclear use. Low-yield weapons are still nuclear weapons. Their effects — blast, heat, radiation, fallout — scale with yield but do not disappear at the lower end of the scale.
Critical, Subcritical, and the Line That Matters
The most important technical distinction in the current testing debate is between critical and subcritical experiments.
A critical nuclear reaction is one in which a self-sustaining chain reaction occurs — fissions begetting fissions in sufficient quantity to produce a nuclear explosion and detectable nuclear yield. Any test that achieves criticality produces nuclear yield, however small, and is prohibited under the Comprehensive Test Ban Treaty (CTBT) and the current US moratorium.
A subcritical experiment uses high explosives to study the behavior of fissile materials — typically plutonium — under extreme pressure and temperature conditions, but stops short of achieving a self-sustaining chain reaction. Zero nuclear yield is produced. The United States has conducted these experiments continuously since 1992 under the Stockpile Stewardship Program, within the parameters of the CTBT, to maintain confidence in aging warhead components without explosive testing. All major nuclear powers conduct them.
Between these two poles sits a contested category: hydronuclear experiments, which involve very small amounts of nuclear yield — fractions of a ton of TNT equivalent — used to study weapons physics. These occupy an ambiguous position under the CTBT and are precisely the category that Assistant Secretary Yeaw’s recent language about “responsible nuclear testing behavior” risks opening the door to. The current policy debate is partly about whether to hold that line or blur it.
The CTBTO and How Verification Actually Works
The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) operates the International Monitoring System (IMS) — a global network of 337 facilities using four complementary detection technologies:
Seismic monitoring detects underground shockwaves from explosions, distinguishing nuclear tests from earthquakes through their waveform signatures
Hydroacoustic monitoring detects underwater sound waves that travel thousands of miles through the oceans
Infrasound monitoring detects low-frequency atmospheric pressure waves from atmospheric or near-surface explosions
Radionuclide detection identifies radioactive particles and noble gases that are signatures of nuclear explosions — and cannot be produced by conventional explosions or subcritical experiments
Together, these systems are capable of detecting yield-producing tests at very low yields — including events well below 1 kiloton. When the Trump administration accused China of conducting a low-yield test on June 22, 2020, the CTBTO’s Executive Secretary stated explicitly that the IMS detected no evidence of a nuclear explosion on that date. That is not a monitoring gap. That is the monitoring system working as designed and returning a negative result.
The IMS has improved by orders of magnitude since the Cold War era. Claims that adversaries can conduct militarily significant nuclear tests while evading this network are not supported by the technical evidence.
H.R.5894 - RESTRAIN Act119th Congress (2025-2026), Sponsor: Rep. Titus, Dina [D-NV-1] (Introduced 10/31/2025)
© 2026 Farooq Hussain