In Busan, South Korea, President Donald Trump hinted at the possibility of the United States resuming nuclear weapons testing after a 30-year hiatus, suggesting it would level the playing field with Russia and China.

The Kremlin acknowledged the ongoing global prohibition against nuclear testing but cautioned that Russia might restart its own tests if other nations do so first.

While there was no concrete evidence that the U.S. would begin actual detonations, Trump’s comments hinted at a potential major change in American policy, though he provided few specifics.

Trump made this statement on social media shortly before a meeting with Chinese President Xi Jinping in South Korea. Later, during a discussion with reporters on Air Force One en route back to Washington, he offered little additional information.

Though the U.S. military routinely tests missiles capable of carrying nuclear warheads, it has not conducted an actual detonation since 1992. The Comprehensive Nuclear Test Ban Treaty, signed but not ratified by the U.S., has been respected by all nuclear-armed countries except North Korea.

Trump suggested, however, that changes were necessary because other countries were testing weapons. It was unclear what he was referring to, but it evoked Cold War-era escalations.

“Because of other countries testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis,” he said in a post on Truth Social. “That process will begin immediately.”

Kremlin warns that Russia will respond in kind if nuclear tests are resumed

Asked about Trump’s comments, Kremlin spokesman Dmitry Peskov reaffirmed an earlier warning from Russian President Vladimir Putin, who said that Moscow would resume nuclear tests if others do so first.

“If someone abandons the moratorium, Russia will act accordingly,” Peskov said in a call with reporters.

The White House did not immediately respond to questions seeking more details. Trump ignored a question from a reporter about his post as he sat face-to-face with Xi in Busan, a meeting that focused on trade issues between the two countries.

When he spoke to reporters later, Trump appeared to be conflating the testing of missiles that deliver a nuclear warhead with the testing of the warheads.

Other countries, he said, “seem to all be nuclear testing” but when it comes to the U.S., “We have more nuclear weapons than anybody. We don’t do testing.”

“I see them testing and I say, well, if they’re going to test, I guess we have to test,” Trump said as he continued speaking to reporters.

Trump was asked where the tests would occur and he said, “It’ll be announced. We have test sites.”

Pentagon officials didn’t immediately respond to questions about the announcement from Trump on the nuclear missile tests.

Russia tests of new nuclear-powered weapons

Putin this week announced that Russia tested a new atomic-powered and nuclear-capable underwater drone and a new nuclear-powered cruise missile. Putin did not announce any tests of Russia’s nuclear weapons, however, which last occurred in 1990.

Peskov, the Kremlin spokesman, emphasized that Russia’s recent tests of the Burevestnik nuclear-powered cruise missile and the Poseidon nuclear-powered underwater drone had nothing to do with the global ban on testing nuclear warheads.

“Regarding the tests of the Burevestnik and the Poseidon, we hope that President Trump was correctly informed about it,” Peskov said. “There is no way it cam be interpreted as nuclear testing.”

Trump did not specifically mention the Russian tests in his post, but alluded to the nuclear stockpiles controlled by both Xi and Putin, saying, “Russia is second, and China is a distant third, but will be even within 5 years.”

Putin in 2023 signed a bill revoking Russia’s ratification of a global nuclear test ban, which Moscow said was needed to put Russia on par with the U.S. The global test ban was signed by President Bill Clinton but never ratified by the Senate.

Earlier this year, Trump signaled he wanted to push his Russian and Chinese counterparts in the other direction, saying he wanted to resume nuclear arms control talks with both countries.

A Chinese Foreign Ministry spokesperson called on the U.S. to refrain from carrying out nuclear tests.

“China hopes the U.S. will earnestly fulfill its obligations under the Comprehensive Nuclear Test Ban Treaty and honor its commitment to suspend nuclear testing,” Guo Jiakun said at a briefing in Beijing.

Despite his announcement that sounded like an escalation, Trump told reporters that he would like to see a “denuclearization and “de-scalation.”

“We are actually talking to Russia about that,” Trump said, though he did not elaborate.

Arms control advocates worried

Daryl Kimball, the executive director of the Washington-based Arms Control Association, quickly criticized the president’s announcement and said Trump was “misinformed and out of touch.”

Kimball, in social media posts, said the U.S. has no reason to resume nuclear explosive testing and it would take at least 36 months to resume testing at the former test site in Nevada, where the last detonations occurred underground.

“By foolishly announcing his intention (to) resume nuclear testing, Trump 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,” Kimball said in a post on X.

Japanese survivors of the U.S. atomic bombings of Hiroshima and Nagasaki at the end World War II condemned Trump’s announcement.

“The act vehemently opposes all countries that are endeavoring to achieve a nuclear-free and peaceful world and absolutely cannot be tolerated,” said Jiro Hamasumi, secretary general of Nihon Hidankyo, a survivors organization that won the 2024 Nobel Peace Prize.