President Donald Trump has directed the United States (US) military to resume nuclear weapons testing for the first time since 1992, saying it is necessary to keep pace with Russia and China.

“Because of other countries testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis,” Trump wrote on social media shortly before meeting Chinese President Xi Jinping in South Korea. He added that the: “process will begin immediately.”

Speaking later aboard Air Force One after the meeting, Trump said: “With others doing testing, I think it’s appropriate that we do also,” as he travelled back to Washington.

The decision reverses more than three decades of US nuclear restraint. The last American test, code-named Divider, took place on 23 September 1992 at the Nevada Test Site, before President George HW Bush issued a moratorium as the Cold War ended.

No country except North Korea has conducted a nuclear test explosion this century, according to the Arms Control Association (ACA), an organisation which seeks to promote effective arms control policies. Its executive director, Daryl G Kimball, sharply criticised Trump’s announcement, saying: “Trump is misinformed and out of touch. The US has no technical, military, or political justification for resuming nuclear explosive testing for the first time since 1992.”

He warned that restarting tests: “will trigger strong public opposition in Nevada, from all US allies, and it could trigger a chain reaction of nuclear testing by US adversaries, and blow apart the Nuclear Non-Proliferation Treaty.”

The announcement comes about 100 days before the New Strategic Arms Reduction Treaty with Russia expires in February 2026, leaving the world’s two largest nuclear powers without a formal arms control framework.