Seoul should treat AUKUS less as a model to copy and more as a cautionary guide as it shapes the terms of Washington’s support for the South Korea’s own nuclear-powered submarine program.
South Korea’s deal with the United States offers a prestige capability, but it also opens many of the same challenges Australia has confronted: long-term costs and contentious non-proliferation politics. The core question for Seoul is not whether it can get nuclear-powered submarines (SSNs), but on what terms and to what strategic effect.
It is tempting to view AUKUS as proof that a non-nuclear-weapon state can obtain SSNs under an upgraded alliance framework. But AUKUS is less a template than a stress test. It shows how quickly ambitious submarine plans meet hard constraints: limited US and British shipyard capacity; stretched budgets; and growing scrutiny from non-proliferation experts. For Seoul, AUKUS should function as a warning label—highlighting which questions must be answered early and which traps to avoid—rather than a simple ‘Australia did it, so can we’ certificate.
The first trap is time. Political messaging around AUKUS created a sense of momentum, but detailed planning has underlined that the program will unfold over decades, with submarines entering service from the early 2030s and operating well into the 2050s. If SSNs are presented as a near-term fix, expectations will be disappointed and public support could sour when voters realise that meaningful capability arrives only over the long term. Seoul should therefore anchor expectations in decades rather than electoral cycles. It should frame SSNs as one pillar of a broader undersea strategy alongside conventional submarines, uncrewed systems and protection of undersea infrastructure.
The second trap is industrial ambiguity. So far, public debate on AUKUS has focused mainly on cost, program deliverability and, to a lesser extent, nuclear proliferation. Official information about how work will be divided among Australian, US and British shipyards, and how production will be sequenced remains limited. However, it is precisely these industrial questions—how to expand capacity without overloading already stressed US and British SSN programs, and what workshare Australia can realistically absorb—that will shape the program’s execution.
South Korea starts from a stronger industrial base: its shipyards build some of the world’s most advanced commercial and naval platforms. But that advantage will matter only if roles are clearly defined early with Washington. Seoul and Washington need to decide whether South Korean shipyards will build full hulls or only non-nuclear sections, whether the US will provide sealed reactor modules or contemplate licensed production, and how maintenance, refits and decommissioning will be handled. These choices will determine not only efficiency and cost, but also where skilled jobs and sensitive know-how reside. Experience in defence-industrial partnerships shows that vague language about ‘industrial cooperation’ quickly becomes politically sensitive once workers and local communities focus on who gets which long-term jobs.
The third and most sensitive trap is non-proliferation. AUKUS has already raised questions about whether naval nuclear propulsion, especially using highly enriched uranium, weakens the Non-Proliferation Treaty by placing weapons-usable material in the hands of non-nuclear allies. For Seoul, this issue is sharper because it lives next to a nuclear-armed North Korea and periodically sees domestic calls for its own bomb. Some treaty states will therefore view a Korean SSN program with suspicion even if it is technically compliant.
Seoul should respond by building safeguards into the program from the start, working with the International Atomic Energy Agency and partners on a regime that is as transparent as possible while preserving operational security. Choices about fuel will be central: low-enriched uranium designs may be harder and costlier but are easier to defend politically than highly enriched uranium arrangements that resemble the AUKUS model.
Clear red lines—no reprocessing, no diversion and robust end-of-life management for reactor cores and spent fuel—should be at the heart of Seoul’s regional diplomacy.
AUKUS also offers alliance management lessons. Canberra has had to sustain domestic support for a multi-decade, multi-hundred-billion-dollar project and reassure regional neighbours that it is not dragging them into a submarine arms race. Seoul faces at least as complex a political geometry. It will need bipartisan support at home and continuity of backing in Washington if the program is to survive leadership changes. It will need to reassure Japan that its SSNs are a stabilising addition to allied deterrence rather than a new source of rivalry, and to keep Southeast Asian and European partners onside by emphasising safeguards, alliance embedding and regional stability rather than national prestige.
Ultimately, the key question is not whether South Korea can technically field SSNs, but what strategic effects they produce. In a best-case scenario, Korean nuclear-powered submarines strengthen integrated deterrence by complicating Chinese and North Korean planning and support coalition efforts to monitor chokepoints and protect critical undersea infrastructure.
In a worst-case scenario, a poorly handled program accelerates a regional arms race, justifies further nuclear and missile advances in Pyongyang, and fuels domestic arguments that if Seoul can manage naval nuclear propulsion, it can manage nuclear weapons as well—undermining both non-proliferation and the alliance.
AUKUS is a reminder that the line between these futures is thin. The South Korea–US deal has opened a historic door, signalling that Washington is willing in principle to extend naval nuclear propulsion cooperation to a second non-nuclear ally. For Seoul, the safest way forward is to treat AUKUS not as a blueprint to copy but as a warning to study and adapt. If it uses that warning well—by setting realistic expectations, clarifying industrial roles, taking non-proliferation politics seriously and managing alliance communications with discipline—South Korea’s nuclear-powered submarine program can strengthen both regional stability and the country’s alliance with the US.