South Korea has formally requested enriched uranium fuel from the United States to power its domestically built nuclear-powered submarine, a significant development announced on November 7, 2025. During summit talks with U.S. President Donald Trump, South Korean President Lee Jae Myung emphasized Seoul’s intent to construct the submarine entirely within South Korea, seeking American assistance solely for uranium fuel supply. Although the U.S. has approved the use of nuclear fuel for the submarine, current bilateral nuclear agreements prevent South Korea from enriching uranium or reprocessing spent nuclear fuel for military use. The South Korean government plans to develop the submarine reactor domestically with uranium enriched to levels suitable for their reactor design, rather than adopting the costly U.S. Virginia-class submarine model. This move aligns with Seoul’s broader effort to enhance maritime security and extend its naval reach, particularly in response to growing regional threats. The agreement marks a milestone in South Korea-U.S. defense cooperation, as South Korea assumes greater responsibility for its defense capabilities while still relying on U.S. technological and fuel support. The announcement has also sparked discussions over where the submarine will be built, with South Korea insisting on domestic construction despite initial U.S. suggestions of a U.S. shipyard build.