The United States has observed a moratorium on nuclear explosive testing since 1992, relying instead on the Stockpile Stewardship Program in place of full-scale detonations to ensure the safety, security, and effectiveness of its nuclear arsenal. It is a mistake to assume that explosive testing is never needed again.
The reality is that Americans live in an increasingly complex threat environment, and the credibility of the nuclear deterrent ultimately depends on America’s ability to respond to technical or strategic surprise. That includes being ready, if necessary, to conduct a nuclear test.
There are multiple and specific conditions under which the US might be compelled to resume underground nuclear testing, each involving serious strategic or technical concerns that cannot be resolved through non-explosive means as directed by the Stockpile Stewardship Program obligations.
From an American strategic perspective, it is possible that a future administration or Congress could determine that the long-standing moratorium on nuclear testing no longer serves American interests. For example, if credible intelligence revealed that an adversary, such as China or Russia, were conducting yield-producing tests, particularly to develop new capabilities or gain strategic advantage, then confidence in the existing deterrence balance could be undermined.
Adversary behavior is a factor the United States cannot ignore. China and Russia maintain active test sites and appear to be positioned to resume testing on short notice. If either nation were to conduct a low-yield test that altered the strategic balance, the US would need to respond—not necessarily by testing, but by demonstrating that it is able. Detecting and interpreting data from these tests may result in the restoration of confidence in the status quo.
Should a nuclear-armed adversary employ or threaten limited nuclear use, a carefully calibrated test could be used to demonstrate resolve, reassure allies, stabilize the situation, and deter further escalation. Such signaling would carry substantial diplomatic consequences and would only be contemplated under extraordinary circumstances.
In addition to strategic drivers that might lead to the resumption of nuclear testing, various technical issues might force America’s hand. For instance, the inability to certify the stockpile through the Stockpile Stewardship Program, such as technical issues with weapons or their components, might also be a driver to resume full-scale nuclear testing.
One such condition would be the emergence of significant doubt about the reliability or safety of an existing warhead type. As the stockpile ages, performance uncertainties can develop in critical components such as plutonium pits, high explosives, or firing systems. If these concerns cannot be resolved through laboratory experiments, modeling, or subcritical testing, a nuclear test might be required to validate performance or ensure safety margins. Such a step would follow a determination by the Nuclear Weapons Council and the national laboratories that non-testing alternatives are insufficient.
A second issue involves the development and certification of new warhead designs. While current policy emphasizes life-extension programs using legacy designs, future geopolitical or technological developments could prompt the US to pursue novel nuclear systems. For example, if the Department of Defense sought a warhead optimized for hypersonic delivery or deeply buried targets, such a design might require full-scale testing for certification—particularly if it deviates from previously tested architectures.
Lastly, there is also the possibility of future weapon development. While current policy focuses on life-extension programs, emerging mission needs may eventually require new designs. If those designs fall outside the range of previously tested systems, the US may have no choice but to test them to certify performance.
Should the United States confront a situation where confidence in warhead reliability or safety can no longer be assured through non-explosive means, or where geopolitical developments erode the credibility of deterrence, a timely and technically sound return to testing may become necessary. However, should the US resume testing for any reason, a great number of challenges will need to be met and overcome.
During the four decades of active nuclear explosive testing, the US developed a strong and thorough testing infrastructure and mindset. As nuclear explosive weapon technology evolved, so did the methods of executing tests and measuring the performance of devices. Facilities, mostly in Nevada, were built and staffed to provide an environment capable of supporting test activities and all the personnel required to perform the tests.
These tests required the expertise of scientists from multiple disciplines, engineers of various specialties, program managers, environmental control technicians, and a wide array of support staff. In addition to the technical workforce, entire teams were responsible for sustaining day-to-day life at remote test sites—providing essential services such as food, water, housing, sanitation, medical support, and logistics.
A rough estimate of the numbers of personnel required to execute an active testing program can be found in a 1981 Department of Energy Nevada Operations Office Newsletter. There were 240 federal employees, 7,100 contractors (laboratory and university personnel), and 11,300 southern Nevada support jobs. Unfortunately, just bringing together the wide variety of personnel needed to execute and support testing is only meeting an obvious challenge. A more subtle challenge is relearning how to keep any explosive test from eaking out of the ground and into the atmosphere.
A resumption of testing would still require the US to meet the obligations of two in-force international treaties; the Threshold Test Ban Treaty (TTBT), which limits the explosive yield of any test to 150 kilotons (kt), and the Limited Test Ban Treaty (LTBT), which bans all above ground and underwater tests. Compliance with the 150 kt limit on explosive yield can be easily maintained because scientists from the national laboratories can confidently ensure the magnitude of the yield will not exceed the limit.
Compliance with the obligations of the Limited Test Ban Treaty presents a different challenge. The cadre of scientific, engineering, and technical experts who would conduct the test are unlikely to have ever faced the challenges of nuclear testing—ensuring the energy and radioactive debris is “contained” in the underground environment.
The cadre of experts who last tested a nuclear weapon, almost 35 years ago, had to “learn” how to meet this unique challenge. Most likely, none of the current cadre has ever been asked to deal with such a large amount of energy released in such a small time increment. Keeping a test contained underground is a vital national interest as a leak of radioactive materials from a nuclear test would cause significant harm to the nuclear enterprise.
Any resumption of nuclear explosive testing would represent a fundamental policy shift with far-reaching implications. A return to testing would affect arms control dynamics, global nonproliferation norms, and the strategic behavior of both allies and adversaries. For these reasons, the threshold for testing remains extraordinarily high, but it is not absolute. Given the challenges facing the United States, dramatic change may come when least expected. A requirement to test a nuclear weapon for strategic or technical reasons may be a part of that change.
James Ragland is a Fellow at the National Institute for Deterrence Studies. Joel Karasikis a contractor for the Defense Nuclear Weapons School. The views expressed are their own.
