BUSAN, South Korea — President Donald Trump ordered the U.S. military on Thursday to immediately resume testing nuclear weapons after a gap of 33 years, minutes before beginning a meeting with Chinese President Xi Jinping.

Trump made the surprise announcement on Truth Social while he was aboard his Marine One helicopter flying to meet Xi for a trade-negotiating session in Busan, South Korea. He said he was instructing the Pentagon to test the U.S. nuclear arsenal on an “equal basis” with other nuclear powers.

“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 posted.

“Russia is second, and China is a distant third, but will be even within 5 years.”

Trump appeared to be sending a message to both Xi, who has more than doubled China’s nuclear warhead arsenal over the past five years, and to Russian President Vladimir Putin, who has tested two new nuclear-powered weapons over recent days.

Russia – which tested a new nuclear-powered cruise missile on October 21, held nuclear readiness drills on October 22 and tested a new nuclear-powered autonomous torpedo on October 28 – said it hoped Trump had been properly informed that Moscow had not tested a nuclear weapon itself.

“President Trump mentioned in his statement that other countries are engaged in testing nuclear weapons. Until now, we didn’t know that anyone was testing,” Kremlin spokesman Dmitry Peskov told reporters.

Putin, who commands the world’s biggest arsenal of nuclear warheads, has repeatedly said that if any country tests a nuclear weapon then Russia will do so too.

No nuclear power – other than North Korea most recently in 2017 – has carried out explosive nuclear testing in over 25 years. Post-Soviet Russia has never tested. The Soviet Union last tested in 1990, the U.S. last tested in 1992 and China in 1996.

China’s Foreign Ministry called for the U.S. to abide by its commitment to a moratorium on nuclear testing and uphold the global strategic balance and stability.

It was not immediately clear whether Trump was referring to nuclear-explosive testing, which would be carried out by the National Nuclear Security Administration, or flight testing of nuclear-capable missiles.

Nuclear Testing Sites to Be Determined Later

Later, on his way back to Washington, Trump said testing was needed to ensure the U.S. keeps up with rival nuclear powers.

“With others doing testing, I think it’s appropriate that we do also,” Trump said on board Air Force One, adding that nuclear test sites would be determined later.

Asked whether the world was entering a more risky phase around nuclear weapons, Trump dismissed the threat, saying U.S. stocks were “well locked up” before adding that he would welcome denuclearisation.

“I’d like to see a denuclearisation because we have so many and Russia’s second and China’s third and China will catch up within four or five years,” he said.

“We are actually talking to Russia about that and China would be added to that if we do something.”

China More Than Doubled Nuclear Arsenal in Last 5 Years

Trump’s decision follows a rapid expansion by China of its nuclear stockpile in recent years, and came just after Russia announced what it called successful tests of the nuclear-powered and nuclear-capable cruise missile and nuclear-powered torpedo.

Trump addressed the Russian moves on his way to Asia earlier this week, telling reporters that Putin should be working to end the war in Ukraine “instead of testing missiles”.

China has more than doubled the size of its arsenal to an estimated 600 nuclear weapons in 2025 from 300 weapons in 2020, according to the Center for Strategic and International Studies, a Washington-based think tank.

It said U.S. military officials estimate that China would have more than 1,000 nuclear weapons by 2030.

The Washington-based Arms Control Association says the United States has a stockpile of 5,225 nuclear warheads and Russia has 5,580.

Putin said on Wednesday Russia had successfully tested a Poseidon nuclear-powered super torpedo that military analysts say is capable of devastating coastal regions by triggering vast radioactive ocean swells.

The Poseidon and the Burevestnik are nuclear-capable and nuclear-powered but the Russian tests did not involve nuclear warheads, according to the Kremlin.

NEGATIVE REACTIONS TO TRUMP’S POST Representative Dina Titus, a Democratic member of the U.S. Congress from Nevada, condemned Trump’s move, saying on X: “I’ll be introducing legislation to put a stop to this.”

Daryl Kimball, director of the Arms Control Association think tank, said it would take the U.S. at least 36 months to resume contained nuclear tests underground at the former test site in Nevada.

“Trump is misinformed and out of touch. The U.S. has no technical, military or political reason to resume nuclear explosive testing for the first time since 1992,” he said on X.

Trump’s announcement, he added, could “trigger a chain reaction of nuclear testing by U.S. adversaries, and blow apart the nuclear Non-Proliferation Treaty.”

In August, Trump said he had discussed nuclear arms control with Putin and wanted China to get involved. Beijing responded by saying it was “unreasonable and unrealistic” to ask the country to join in nuclear disarmament negotiations with the two countries since its arsenal was much smaller.

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(Reporting by Trevor Hunnicutt, Ismail Shakil, Kanishka Singh and Andrea Shalal; Additional reporting by Guy Faulconbridge in Moscow; Editing by Stephen Coates, Kate Mayberry and Mark Heinrich)