The United States and South Korea have agreed to deepen cooperation on Seoul’s pursuit of a nuclear-powered submarine, as Washington signals a shift toward a more limited frontline role in deterring North Korea and urges its key ally to assume greater responsibility for regional security.
US Under Secretary of Defense for Policy Elbridge Colby and South Korean Defence Minister Ahn Gyu-back reached the understanding during talks in Seoul on Monday (Jan 26), South Korea’s defence ministry said in a statement.
Colby is visiting South Korea on his first overseas trip since assuming the post, underscoring the importance Washington places on alliance burden-sharing amid evolving security challenges on the Korean Peninsula. The discussions come days after the Pentagon released its new National Defense Strategy, which explicitly states that the United States expects South Korea to take primary responsibility for deterring North Korea, with the US playing a “more limited” supporting role.
According to the defence ministry, both sides agreed that cooperation on a nuclear-powered submarine would significantly enhance South Korea’s ability to lead the defence of the peninsula while also elevating the overall strength of the US–South Korea security alliance. Nuclear-powered submarines would give Seoul extended endurance, greater stealth, and improved surveillance capabilities, particularly against North Korea’s growing missile and submarine-based threats.
Ahn also pressed for faster progress on the long-delayed transfer of wartime operational control (OPCON) from US forces to the South Korean military. He called for closer coordination on follow-up alliance measures to ensure a smooth transition and maintain deterrence credibility, the ministry said.
Colby, the Pentagon’s top official overseeing defence and foreign policy planning, praised South Korea as a “model ally” in a post on X upon arriving in Seoul. He highlighted Seoul’s commitment to increasing defence spending in line with US regional strategy.
South Korea hosts around 28,500 US troops and last year pledged to raise defence spending to 3.5 per cent of gross domestic product. US officials have repeatedly welcomed the move as evidence of Seoul’s willingness to shoulder greater responsibility in countering North Korean threats.
Colby is also expected to visit Japan as part of his Asia trip, according to media reports, as Washington seeks to strengthen coordination among its key allies in the region.
