U.S. President Donald Trump announced Thursday that Washington will share its closely held nuclear technology with Seoul to allow it to build nuclear-powered submarines in the United States, a move that could have implications for Japan’s own defense policies.

“South Korea will be building its nuclear-powered submarine in the Philadelphia Shipyards (officially known as Philly Shipyard), right here in the good ol’ U.S.A,” Trump posted Thursday on his Truth Social account, referring to the commercial shipbuilder acquired by the Hanwha Group late last year as part of South Korea’s ongoing investments in the U.S. shipbuilding industry.

"I have given them approval to build a nuclear-powered submarine, rather than the old fashioned, and far less nimble, diesel powered submarines that they have now," Trump wrote.