South Korean President Lee Jae-myung and U.S. President Donald Trump are meeting in Seoul this week to discuss a nuclear-powered submarine agenda [1].

The talks aim to address critical capability gaps in South Korea's current diesel submarine fleet. Nuclear propulsion would allow for longer submerged durations, which is essential for monitoring regional threats.

This meeting marks the first follow-up to an agreement reached during a Korea-U.S. summit in October 2023 [2]. The discussions were delayed for approximately six months before the current session scheduled for the week of May 31, 2026 [3].

A primary focus of the agenda is the domestic construction of the vessels. A South Korean government spokesperson said the plan involves the use of low-enriched uranium below 20% enrichment [4]. This specific technical threshold is a key component of the proposed nuclear cooperation agreement revision.

President Lee Jae-myung noted the limitations of current technology in the region. "Diesel submarines have lower diving capabilities, which limits tracking activities of North Korean or Chinese submarines," Lee said [5].

Despite the shared goal of strengthening maritime security, the United States has reportedly expressed concern over a specific, undisclosed issue regarding the program [1]. The two nations are working to resolve this friction to ensure the program can move forward without violating international nuclear norms.

The revision of the nuclear cooperation agreement remains a central hurdle. Without a formal change to these rules, South Korea's ability to enrich uranium for naval propulsion would remain restricted under current treaties [1].

“"Diesel submarines have lower diving capabilities, which limits tracking activities of North Korean or Chinese submarines,"”

The pursuit of nuclear-powered submarines represents a significant shift in South Korea's defense posture, moving toward a more autonomous deterrent against North Korea and China. However, the U.S. concern suggests a tension between providing security guarantees and preventing nuclear proliferation. The outcome of these talks will determine if South Korea can bypass the limitations of diesel propulsion while remaining within the bounds of the U.S.-led non-proliferation regime.