President Lee Jae Myung highlighted the pursuit of nuclear-powered submarines, citing China and North Korea, during his October 29 summit with US President Donald Trump in Gyeongju. The United States approved South Korea's construction of nuclear-powered attack submarines and pledged cooperation on fuel sourcing. The move has sparked debates over regional security and nuclear nonproliferation.
During the October 29, 2025, summit in Gyeongju, North Gyeongsang Province, between South Korean President Lee Jae Myung and US President Donald Trump, Lee surprised observers by explicitly naming China, alongside North Korea, as a key rationale for pursuing nuclear-powered submarines. He argued that diesel-powered submarines are too slow for the South Korean Navy to effectively track and outmaneuver North Korean and Chinese vessels, requesting US support for uranium fuel for naval reactors. Lee aims to build several conventionally armed, nuclear-powered attack submarines to defend maritime borders in the East and West Seas, stating, “Should this happen, the U.S. would be able to ease part of the defense burden it currently carries.”
Beijing swiftly rebuked the pitch. Chinese Foreign Ministry Spokesperson Guo Jiakun said on October 30, “China hopes that South Korea and the United States will earnestly fulfill their nuclear nonproliferation obligations and do things that promote regional peace and stability, not the opposite.” At home, Lee's identification of China as a threat contrasted with his past caution, sparking speculation about his motives.
The joint fact sheet released last week confirmed US approval: “The United States has given approval for the ROK to build nuclear-powered attack submarines. The United States will work closely with the ROK to advance requirements for this shipbuilding project, including avenues to source fuel.” South Korea plans low-enriched uranium (LEU) naval reactors, akin to those in its commercial plants under the US-ROK 123 Agreement, which supplies over 30 percent of national electricity. However, the pact requires consultations via a High-Level Bilateral Commission for new developments.
Retired Navy Capt. Park Bum-jin, a professor at Kyung Hee University, viewed Lee's rhetoric as calculated to secure bipartisan US support. Alternatives like partnering with France were noted by KAIST's Lee Jeong-ik but deemed risky for the US alliance, as seen in Australia's AUKUS shift. Experts like Retired Lt. Gen. Chun In-bum and US analysts Bryan Clark and Bruce Bennett highlighted challenges from domestic anti-nuclear sentiment and proliferation concerns, though naval reactors are NPT-compliant.