The following article is part of a series of APLN analyses by experts and members assessing the implications of the Australia-UK-US (AUKUS) deal.

Some American allies were taken by surprise when Australia, the UK, and the United States, announced a wide-ranging defence deal, dubbed AUKUS. Among the many items of the agreement, the most concerning one is that Australia will be supplied with nuclear submarines from either the UK or the United States.

The deal has sparked concerns about the future of nuclear proliferation. There are several reasons to believe that South Korea will be the next marine power in the Asia-Pacific to purchase or develop nuclear submarines. It is necessary that the international community recognizes the risk that this poses to global non-proliferation norms, and seek ways to forestall what may be a cascade of submarine nuclear proliferation in the Asia-Pacific.

A troubling record

South Korean nuclear proliferation has gone relatively unnoticed next to the brazen proliferation activities of its northern neighbour. But this does not mean that it is not a cause for concern, because South Korea has a troubling record on nuclear proliferation. It came under the microscope for its nuclear research activities less than two decades ago. In 2004, the country declared significant – and previously unknown – proliferation activities during the 1970s and 1980 to the International Atomic Energy Agency (IAEA), and also revealed that it had attempted to enrich uranium as late as 2000. Around this time, it also attempted to initiate a program for nuclear submarine propulsion, but it proved short-lived.

Today, there are other worrying signs. In 2017, 60 per cent of South Koreans who responded to a Gallup poll, said that they favoured South Korea acquiring nuclear weapons. In 2021, a poll conducted by the Asan Institute, a South Korean think tank, suggested that “[n]early 70% of the respondents supported developing indigenous nuclear capability and over 61% supported reintroducing tactical nuclear weapons.”

Some South Korean politicians, including a potential presidential nominee, have also begun to shift the public conversation towards acquiring home-grown nuclear weapons, or at least to re-stationing US nuclear weapons on the Korean peninsula.

This context is important to understand the risks of South Korea acquiring nuclear-powered submarines. Nuclear-powered submarines are not covered by the Non-Proliferation Treaty (NPT) to which South Korea is a party and thus represent a much lower threshold for nuclear proliferation than a wholesale nuclear weapons program.

Korean demand, French supply?

South Korea does have an agreement with the United States since 2015 that regulates nuclear cooperation between the two countries. The agreement does not cover nuclear propulsion, but in light of the AUKUS deal, it is likely that South Korean policymakers will press for such an agreement. ‘If Australia can have nuclear subs, why can’t we?’ South Korea may be even be interested in combining nuclear propulsion with its recently demonstrated submarine launched missile (SLBM) capacity.

France may be a willing provider. It lost a large contract to the AUKUS deal, and it is surely surveying other prospective customers. South Korea is very likely a candidate – already in 2018, it was reported that South Korea explored the potential for purchasing nuclear submarines from France. The French ambassador to Seoul even indirectly broached the topic at a press-meeting with South Korean media, noting that “France and the United States are the only countries that have all the technology related to nuclear submarines,” adding that “from nuclear submarines or aircraft carriers, we don’t need any US technology.” Through the now-defunct deal with Australia, France was meant to provide diesel-electric submarines. With the non-proliferation norm already damaged, France may very well be willing to sell South Korea submarines of a more advanced, nuclear-kind.

The AUKUS deal thus has two mutually reinforcing effects on these two American allies: it undermines South Korean commitment to nuclear non-proliferation agreements with the United States, and it impels France to further rethink its strategic relationships. Even before the AUKUS debacle President Macron has been a strong advocate for European strategic autonomy, and the international humiliation of the AUKUS deal has strengthened that conviction.

How to clear the muddy waters ahead

On the bright side, if South Korea was to acquire nuclear submarines from France, their reactors would likely run on Low-Enriched Uranium (LEU). While LEU poses a larger risk for diversion, as reactors built to run on LEU need to be refueled more often, this material is not immediately useable for weapons production, and South Korea already possesses large quantities of it through its civilian nuclear program. Still, South Korea’s poor past record on non-proliferation shows that the risk remains that nuclear material which is not subject to IAEA’s monitoring measures (safeguards) might be diverted to proscribed uses.

For this reason, the short to mid-term outcome is unlikely to be a South Korean nuclear weapons program. Instead, we are likely to witness the undermining of a non-proliferation norm in a country where it is already weakened, and in a region which is undergoing a significant arms race.

China is already viewing the AUKUS deal with concern. Whether South Korea acquires nuclear submarines with or without US approval is hardly going to matter much to China; the prospect of another US ally with stealthy submarines and SLBM capability is unlikely to improve its already suspicious relationship with the United States. The AUKUS deal may therefore prove to be a strategic blunder for the United States, both in terms of how it weakens non-proliferation norms, and how it may incite stronger than anticipated reactions from China.

To be sure, nuclear submarine deals take a long time to work out, and an even longer time to complete – the first boats probably won’t be delivered to Australia until 2040. This means that there is still time to contain the normative fallout of the AUKUS deal. As parties to the NPT prepare for the upcoming review conference, postponed to 2022, it would probably be vain to hope that they close the submarine-loophole which gives parties the right to use nuclear fuel for military purposes. However, they should still recognize the seriousness of the issue and make sure to address it among the recommendations provided in the final document. This would not amount to a legal fix, but a political way of addressing an increasingly politicized issue.

Disclaimer: The opinions articulated above represent the views of the author(s) and do not necessarily reflect the position of the Asia Pacific Leadership Network or any of its members. The APLN’s website is a source of authoritative research and analysis and serves as a platform for debate and discussion among our senior network members, experts and practitioners, as well as the next generation of policymakers, analysts and advocates. Comments and responses can be emailed to apln@apln.network.

Image: Sailors onboard the Korean submarine LEE CHUN stand at the ready, as they prepare to go pier-side in Apra Harbor, Guam. Photo by Craig P. Strawser