In a dramatic policy shift, U.S. President Donald Trump has ordered the immediate resumption of nuclear weapons testing by the United States, ending a 33-year moratorium. Media reports says the announcement came just minutes before his scheduled meeting with Chinese President Xi Jinping in Busan, South Korea. President Trump made the declaration via his Truth Social account while aboard Marine One en route to the summit. He stated that the move is intended to ensure the U.S. maintains nuclear parity with other major powers. “I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis. That process will begin immediately," Trump wrote. Reuters reports that speaking later aboard Air Force One on his return to Washington, Trump defended the decision, saying it was necessary in light of nuclear developments in rival states. "With others doing testing, I think it's appropriate that we do also," he said, adding that the specific locations for nuclear tests would be announced at a later date. When asked whether the world was now entering a more dangerous era of nuclear proliferation, Trump played down the risks, insisting the U.S. nuclear stockpile was “well secured.” He also expressed continued support for global denuclearization efforts. The decision follows heightened nuclear activity from both Russia and China. Moscow recently claimed a successful test of a nuclear-powered cruise missile and the Poseidon super torpedo, a nuclear-powered underwater weapon designed to cause large-scale destruction in coastal areas. Reuters reports that according to the Center for Strategic and International Studies, a Washington-based think tank, China has reportedly doubled its nuclear arsenal, expanding from approximately 300 warheads in 2020 to an estimated 600 in 2025. The Washington-based Arms Control Association says the United States has a stockpile of 5,225 nuclear warheads and Russia has 5,580.