In late October, President Trump declared on social media that he had ordered the Pentagon “to start testing our nuclear weapons,” thereby ending the voluntary moratorium imposed by the Bush Sr. administration in 1992. The president portrayed his decision as a response to “other countries’ testing programs” and singled out Russia and China, which he later claimed had conducted small-scale underground detonations covertly.
One month later, and the administration has yet to take concrete steps forward. However, the resumption of America’s nuclear testing could have dangerous repercussions for the U.S. and the world.
Trump’s statement sounded like an improvisation. He surprised his aides. He erroneously claimed that the U.S. (not Russia) had the world’s largest nuclear arsenal. He mistakenly suggested that the Department of War (not the Department of Energy) handled nuclear testing. Finally, his Secretary of Energy quickly contradicted him.
As he seemed to suggest, several reports have accused Moscow and Beijing of conducting small “supercritical nuclear tests” to improve their warheads, exploiting long-standing ambiguities about what constitutes a test. But those allegations are difficult to verify. Regardless, the data such tests can provide is limited and pertains to nuclear safety rather than weapons enhancement.
Moreover, resuming nuclear tests would be politically costly. Although more easily contained than underwater, atmospheric, and outer-space detonations, underground explosions, the only option available since Washington signed the Partial Test Ban Treaty in 1963, could release radioactive particles across Nevada (which hosts America’s sole authorized testing site), other parts of the U.S., and abroad. In fact, many Americans still suffer from the consequences of Cold War testing, including abnormal cancer rates, contaminated soils, and poisoned waters. Nuclear testing has also had lasting humanitarian and ecological consequences in other world regions, which would make new tests controversial there as well.
U.S. officials estimate that preparing an underground atomic explosion would take 24 to 36 months. However, this timeline could change given the authorities' long-standing de-prioritization of readiness, the “disrepair” of America’s facilities, and a severe workforce deficit. Political resistance and legal actions could cause additional delays.
For all those reasons, whether the Trump administration pursues nuclear testing remains subject to speculation. The U.S. might continue testing specific nuclear parts and systems. It could resume “subcritical experiments” (stopping short of physical bursts). Washington could also expand its testing programs for missiles, bombers, and other delivery platforms. President Trump might also be trying to project strength for deterrence purposes and to pressure Russia and China into trilateral arms-control talks.
Yet the prospect of renewed nuclear testing cannot be discarded. As of mid-November, the White House still insisted that “nothing ha[d] been eliminated from consideration.” The Project 2025 initiative advocated for “immediate test readiness.” The first Trump administration itself debated nuclear testing.
Some senior experts and ex-officials have argued for years that new tests would help Washington verify that its decades-old nuclear systems and components still function, optimize its “novel [arms] designs,” and deter Beijing and Moscow as they race towards hypersonic weapons.
Those arguments could gain ground as the national security community frets about a “looming two-nuclear-peer threat environment.” Russia has repeatedly indulged in nuclear “saber rattling,” and recently tested a nuclear-capable cruise missile (Burevestnik) and nuclear-powered underwater drone torpedo (Poseidon). Likewise, the Department of War expects China to deploy 1,500 nuclear warheads by 2035.
Yet resuming nuclear testing would be strategically dubious, and even dangerous. Washington may antagonize China and Russia. For all their provocations, the latter have long worried about America’s search for “nuclear primacy,” including its doctrinal changes, pre-emptive strike capabilities, and ballistic missile defense systems.
Moscow, which “de-ratified” the Comprehensive Test Ban Treaty (CTBT) in 2023 and has expanded its testing facilities, announced it would “retaliate immediately” should the U.S. proceed with an atomic detonation. China’s response was more moderate. Yet, like Washington, Beijing did not ratify the CTBT, has upgraded its testing installations in Xinjiang, and saw President Trump call for new tests immediately before he met Xi Jinping in South Korea.
In sum, renewed testing could lead great powers to abandon arms control, renounce risk-mitigation, and accelerate the nuclear arms race.
New tests may even weaken the United States. Since 1992, American scientists have used simulations, “high-energy lasers,” and supercomputers to maintain the country’s arsenal, and know much more today than during the Cold War. By contrast, because they conducted fewer tests and had far less advanced analytical tools, Moscow and, especially, Beijing would benefit disproportionately from new nuclear explosions.
Additionally, nuclear-armed Israel, India, North Korea, and Pakistan, which never signed the CTBT, might follow suit. New Delhi may want to reciprocate Beijing’s moves, which, in turn, may incentivize Islamabad.
Iran, whose leaders denounced Trump’s statement as “irresponsible,” could also review its options. While its nuclear program has survived the American-Israeli strikes of June 2025 and even showed signs of resurgence, the country is facing renewed UNSC sanctions and is at risk of another conflict with Israel. In that context, new American nuclear tests might convince Tehran to race for the bomb.
Instead of floating dangerous ideas, Washington should try to re-ignite the arms control talks interrupted by China in July 2024 due to disagreements over Taiwan. Above all, it should exploit Vladimir Putin’s recent overtures for a temporary extension of the New START Treaty, the last-standing arms control agreement between the world’s two largest nuclear powers.
Thomas Cavanna is a Non-Resident Fellow at Defense Priorities.
