President Donald Trump authorized South Korea to develop nuclear-powered submarines at a Philadelphia facility owned by Hanwha Ocean, marking an unusual extension of America’s closely guarded naval technology to another ally.
The president announced the decision Thursday following trade negotiations with South Korean President Lee Jae Myung in Gyeongju, where the two countries finalized a $350 billion investment package. Trump said the submarines would replace South Korea’s diesel-powered fleet and be constructed at Hanwha Philly Shipyard, which the Korean conglomerate purchased for $100 million in late 2024.
The arrangement raises questions about execution timelines and technical feasibility. The Philadelphia facility currently builds commercial vessels and lacks the infrastructure for nuclear submarine construction—a capability that would require years to develop and significant workforce expansion. Australia faces similar challenges under the AUKUS agreement, with its nuclear submarine program extending into the 2040s.
The deal requires amending the bilateral nuclear cooperation treaty to permit uranium enrichment above current 20 percent limits. American naval reactors use weapons-grade uranium enriched to approximately 94 percent, according to defense analysts. Congressional review of any nuclear material transfers could take 90 days.
Hanwha Ocean committed to investing $5 billion in modernizing the Philadelphia yard, part of Seoul’s broader pledge to direct $150 billion toward American shipbuilding capacity. The company has positioned itself to pursue U.S. Navy contracts after acquiring the facility.
Regional implications remain uncertain, with analysts suggesting China will likely criticize the move while Japan may accelerate its own non-conventional submarine programs.
