President Donald Trump has ordered the Pentagon to resume U.S. nuclear weapons testing after more than three decades without explosive tests, a move that experts say could unravel global nonproliferation efforts and risk widespread radioactive contamination.
Trump made the announcement in a short post on Truth Social shortly before meeting Chinese President Xi Jinping in Busan, South Korea. “Because of other countries testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis. That process will begin immediately,” Trump wrote. He added, “The United States has more Nuclear Weapons than any other country,” a claim contradicted by independent data showing Russia possesses a slightly larger stockpile.
According to the Washington-based Arms Control Association, the United States has 5,225 nuclear warheads, compared with Russia’s 5,580. Trump’s post continued, “Russia is second, and China is a distant third, but will be even within 5 years.”
It remains unclear whether Trump’s order refers to full-scale explosive nuclear tests or to subcritical and flight testing of nuclear-capable missiles. Speaking to reporters aboard Air Force One after his meeting with Xi, Trump confirmed that details were forthcoming. “We don’t do testing. We’ve halted it years, many years ago. But with others doing testing, I think it’s appropriate that we do also,” he said. Trump added that the sites for the tests “would be determined later.”
The announcement marks a sharp departure from long-standing U.S. policy. The last underground nuclear explosion conducted by the United States took place in 1992 in Nevada. The order appears to disregard the Comprehensive Nuclear Test Ban Treaty, which the United States signed in 1996 but never ratified. Although unratified, Washington has observed the treaty’s prohibition on explosive testing for more than thirty years.
International reaction was swift. China’s Foreign Ministry urged the United States to “earnestly fulfill its obligations under the Comprehensive Nuclear Test Ban Treaty and honor its commitment to suspend nuclear testing.” A senior Russian lawmaker told state news agency RIA that Trump’s decision would usher in “a new era of unpredictability and open confrontation.”
Beatrice Fihn, former executive director of the International Campaign to Abolish Nuclear Weapons, condemned the decision as “incredibly stupid.” Fihn said, “This would have real, devastating impact for Americans. It will harm, kill, and poison people. It has been estimated that past US nuclear testing killed as many Americans as its bombs on Hiroshima and Nagasaki did.” She added that “even if such nuclear tests are conducted underground, this poses a risk in terms of the possible release and venting of radioactive materials, as well as the potential leakage into groundwater.”
Arms control experts described Trump’s justification as unfounded. “Trump is misinformed and out of touch,” said Daryl Kimball, executive director of the Arms Control Association. “The U.S. has no technical, military, or political reason to resume nuclear explosive testing for the first time since 1992.” Kimball added, “It would take least 36 months to resume contained nuclear tests underground at the former test site in Nevada.”
Kimball warned that “no country except North Korea has conducted a nuclear test explosion in this century” and that Trump’s announcement “will trigger strong public opposition in Nevada, from all U.S. allies, and it could trigger a chain reaction of nuclear testing by U.S. adversaries, and blow apart the Nuclear Nonproliferation Treaty.”
Domestic opposition to the announcement emerged immediately. Nevada Democratic Representative Dina Titus wrote on X, “I’ll be introducing legislation to put a stop to this.” Nevada was the site of 928 U.S. nuclear tests during the Cold War, leaving a legacy of radioactive fallout that continues to affect residents and tribal communities.
Tilman Ruff, a board member of International Physicians for the Prevention of Nuclear War, said a resumption of testing “would be extremely dangerous for humanity.” Ruff wrote, “It would almost inevitably be followed by tit-for-tat reciprocal announcements by other nuclear-armed states, particularly Russia and China, and cement an accelerating arms race that puts us all in great jeopardy.” He added that “it would also create profound risks of radioactive fallout globally. Even if such nuclear tests are conducted underground, this poses a risk in terms of the possible release and venting of radioactive materials, as well as the potential leakage into groundwater.” Ruff concluded, “It’s really an extraordinarily dangerous time in history.”
Manpreet Sethi, a member of the Science and Security Board at the Bulletin of the Atomic Scientists, said earlier this year that “the US has abdicated its role as a voice of caution” as “the risk of nuclear use continues to grow due to capabilities building up and treaties breaking down.” Sethi added that the United States “seems inclined to expand its nuclear arsenal and adopt a posture that reinforces the belief that ‘limited’ use of nuclear weapons can be managed.” She warned that “such misplaced confidence could have us stumble into a nuclear war.”
The United States opened the nuclear era in 1945 with the test of a 20-kiloton bomb in New Mexico and later dropped atomic bombs on Hiroshima and Nagasaki. Since then, major nuclear powers have refrained from testing for decades, with the exception of North Korea, which last conducted a test in 2017.
Trump’s directive follows a period of heightened nuclear tension. Russia recently announced successful tests of its nuclear-capable Burevestnik cruise missile and Poseidon nuclear-powered torpedo, while China has expanded its arsenal from 300 warheads in 2020 to around 600 in 2025, according to the Center for Strategic and International Studies. U.S. officials estimate that China could exceed 1,000 nuclear weapons by 2030.
Kimball warned that restarting U.S. nuclear testing could “trigger a chain reaction of nuclear testing by U.S. adversaries,” undoing decades of restraint. Experts caution that beyond geopolitical consequences, renewed testing could bring long-term environmental and health damage. As Fihn noted, even underground explosions risk venting radiation into air and groundwater, threatening communities far beyond the test sites.
Trump, however, dismissed concerns. “With others doing testing, I think it’s appropriate that we do also,” he told reporters. The president’s statement reflects his broader approach to nuclear policy, which prioritizes parity with rivals over international cooperation.
Ruff wrote that restarting nuclear tests “would be extremely dangerous for humanity.” For nonproliferation advocates and scientists who have worked to prevent nuclear escalation since the end of the Cold War, Trump’s directive marks what they describe as a grave turning point.
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