South Korea, Australia can learn from each other over nuclear submarine pathways

Euan Graham

Australia and South Korea are both acquiring nuclear-powered attack submarines, a parallel step-change in their conventional deterrent capability. Though their discrete pathways to realise this common goal reflect different strategic circumstances and problems, they can still usefully learn from each other’s experience and cooperate.

Viewed from Australia, where AUKUS still stirs controversy five years after the tripartite initiative was announced, South Korea’s recently announced framework to acquire nuclear powered submarines is a refreshing contrast.

Unlike Australia, which is acquiring 2 different types of nuclear-powered submarine in close partnership with the U.S. and U.K., President Lee Jae Myung’s administration is seeking a largely made-in-Korea solution, with limited assistance from the U.S.

To be fair, Seoul had no other realistic choice. Despite claims by U.S. President Donald Trump that Korea’s future nuclear submarines would be built in Philadelphia, following the surprise announcement on the sidelines of last October’s APEC summit in Gyeongju, Seoul has since pivoted the project to a more domestic framing. This pragmatic adjustment is essential to the project’s viability, as America’s submarine industry is currently struggling to fulfil the U.S Navy’s order book. Any remaining bandwidth for allies will be taken up by AUKUS, which includes a commitment to transfer 3 used Virginia-class attack submarines to Australia in the 2030s.

Despite obtaining Donald Trump’s all-important consent to develop nuclear propulsion for naval purposes, it is clear that Seoul will receive less tangible external assistance than Australia, via AUKUS. U.S. material assistance for the Korean submarine program is likely to be limited to the provision of low-enriched uranium fuel, thus minimizing weapons proliferation risks. Seoul still faces the daunting challenge of designing and building its own naval reactors and propulsion system. Even with a civil nuclear sector and a sizeable conventional submarine industry serving as a foundation, this multi-decade undertaking will stretch South Korea’s scientific, industrial and fiscal capacities to their limits.

Given the scale of the challenge, Seoul’s self-confident embrace of the nuclear submarine project as within its self-reliant grasp is commendable. This is a challenge that South Korea intends to shoulder without undue reliance on allies and partners. And it is doing so on a similar timeline to the new SSN-AUKUS submarines, which are meant to enter service from around 2040. Although Australia has a 5-year headstart on South Korea, Seoul could even get there first.

South Korea’s willingness to take ownership of the nuclear submarine program as a national endeavor is the clearest difference from Australia’s submarine "optimal pathway" under AUKUS, which remains fundamentally dependent on the ability and willingness of both the U.S. and U.K. to deliver Australia’s future submarine capability. Canberra’s ability to leverage its closest allies is its main advantage over South Korea, as Australia lacks the wherewithal to do it alone. But it is also a weakness, as AUKUS has become an excuse for critics to blame Canberra’s American and British partners, instead of squarely owning the collective failure of successive Australian governments to recapitalize the country’s ageing submarine fleet. Furthermore, AUKUS has slipped from being a whole-of-government endeavour, to one owned and resourced by Defence.

Australia can still offer a much-needed lesson in bipartisanship. For South Korea’s most likely shortfall for the submarine program is not technical in nature, but political. The Lee administration needs to build bipartisan support, as without this the nuclear submarine project could wither and fail. Given South Korea’s fractious politics, Lee cannot hope to bind the hands of future conservative presidents unless he makes a conscious effort to build consensus during the remainder of his single term in office. AUKUS remains divisive in Australia, but it has already survived one change of government because both major parties have backed it as a cornerstone of their defence policies – though the Greens are opposed.

No such bipartisanship exists in South Korea. The ambition to acquire nuclear-powered submarines has been associated mainly with the left, while conservative administrations have shown less interest. The costs associated with nuclear submarines are so great that both sides of politics need a sense of ownership over this long-term national endeavor, especially given the glaring absence of any projected cost within the government’s blueprint. Cancellation would impose serious reputational as well as financial costs on South Korea.

Though AUKUS and the Korean nuclear submarine projects are proceeding on parallel tracks, Canberra and Seoul can still actively cooperate. Australia’s diplomatic precedent has already been useful for South Korea as it starts to develop non-proliferation safeguards with the IAEA. Given North Korea’s increasing nuclear threat, along with China’s strategic buildup, Seoul must work hard to reassure other countries that it intends to honour its pledge not to develop nuclear weapons. Australia has valuable experience to share here and there is scope for both governments to coordinate their non-proliferation assurances to nuclear-skeptic Pacific and Southeast Asian nations. Japan will be keeping a watchful eye on South Korea’s progress, as the country most likely to follow suit with its own nuclear-propulsion plans in due course.

Finally, Australia and South Korea should step up military cooperation in submarine and anti-submarine warfare. They may not share all the same threat perceptions, but there is enough of an operational overlap to be mutually beneficial. Ultimately, only the aggregation of advanced allied and partner military capabilities can maintain regional stability and deterrence.

Euan Graham is an analyst specialising in Indo-Pacific defence and security, including the Korean Peninsula. He’s an expert associate at the Australian National Security College, adjunct fellow at the Council on Geostrategy and senior fellow at the Australian Strategic Policy Institute.