President Donald Trump has called on US military leaders to resume testing US nuclear weapons in order to keep pace with other countries such as 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, he wrote on social media just before meeting with Chinese President Xi Jinping in South Korea.

The US has more nuclear weapons than any other country, with Russia second and China a distant third. It has not conducted nuclear weapons testing since 1992.

Trump's announcement comes just days after he criticized Russia for testing a nuclear-powered missile. The nuclear test sites will be determined later, according to Trump.

Experts warn that this could trigger a new arms race, as no country has conducted a nuclear test explosion this century, apart from North Korea. Trump's statement marks a significant reversal of US policy since the Cold War.

Concerns have also been voiced regarding the implications of such tests on global stability and protest from various political leaders. Trump's administration has previously emphasized the catastrophic nature of nuclear weapons, fostering a complex dialogue on the future of nuclear arms.