President Donald Trump announced on Wednesday that the United States will share “nuclear propulsion technologies” with South Korea, marking a significant shift in defense cooperation. The decision comes as part of broader trade negotiations and highlights growing strategic ties between Washington and Seoul.

The move is historic, as the U.S. has previously only granted nuclear propulsion knowledge to the United Kingdom and Australia under the 2021 AUKUS agreement. Trump emphasized that South Korea’s navy will use the technology to build at least one nuclear-powered submarine, a project set to begin at Hanwha Philly Shipyard in Pennsylvania. The facility, owned by a South Korean company, is not currently equipped for nuclear material handling or military shipbuilding.

Trump framed the announcement as part of a trade deal that includes South Korea’s $350 billion investment in the U.S. economy. He also revealed plans to resume nuclear weapons testing, citing concerns over China’s expanding arsenal. In a social media post, Trump praised the collaboration, stating, “Shipbuilding in our Country will soon be making a BIG COMEBACK.”

The president defended his decision to restart tests, arguing that other nations’ advancements necessitate U.S. action. He expressed interest in global de-nuclearization but stressed that dialogue with China and Russia remains ongoing.