Description
At the ROK-US summit in October 2025, President Lee Jae Myung made an unusually direct request to President Trump: US support for Seoul’s pursuit of nuclear-powered attack submarines (SSNs). Seoul’s interest in conventionally armed SSNs dates back to the 1990s; the covert “362 Project,” launched in 2003, stalled amid technological limitations and US nonproliferation objections. This renewed push offers a window into middle-power strategy in the Trump era. The paper argues that waning confidence in US extended deterrence—intensified by transactional alliance management, burden-sharing disputes, and volatile crisis signaling—has shifted Seoul’s calculus toward SSNs as a survivable, non-nuclear means that enhances deterrence without overt proliferation. Yet the binding constraints are legal and institutional, not technical. South Korea operates under dense obligations: the NPT, IAEA safeguards, the INFCIRC/153 paragraph 14 “naval propulsion” provision, NSG guidelines, and, critically, the 2015 US–ROK 123 Agreement, which limits enrichment and reprocessing without prior US consent. The paper analyzes feasible pathways—such as LEU-based propulsion, fuel leasing and take-back, auditable paragraph 14 arrangements, and enhanced transparency—and the alliance bargaining they require. It concludes that an SSN program is politically attractive as a hedge, but legally viable only if embedded in strengthened safeguards and predictable US–ROK consultations that protect nonproliferation credibility while addressing South Korea’s deterrence needs.