President Trump recently announced support for South Korea’s plans to build nuclear-powered submarines.

This is a triumph for Korea’s new President Lee Jae Myung, generally regarded as less close to Washington and more interested in dialogue with China than his predecessor.

The deal is reported to have been part of a complex package of economic and security outcomes, including possibly a commitment to construct submarines in the US at a Korean owned shipyard.

Also, recently a Japan defence ministry report argued the case for a submarine program employing a new generation of propulsion – presumably nuclear. Japan’s new Prime Minister Sanae Takaichi is on record as favouring the idea.

South Korea’s decision to acquire nuclear-powered submarines will add to the pressure on Japan. And it looks likely the two will travel different paths. Japan is contemplating a submarine with vertical missile launch capability, allowing larger and wider ranging missiles, thus requiring a larger boat.

Both countries have ample expertise and capacity to build the submarines. They also have the technology to build their own nuclear propulsion reactors. However both could greatly benefit from the US’ 70 years of experience with submarine nuclear propulsion technology.

Fuel for the reactors

The fuel, enriched uranium, is another matter. Japan already has enrichment capability and could make its own fuel – either low enriched uranium (like France) or weapon grade (like US, UK and what will be used in AUKUS submarines), depending on the reactor design chosen.

But Japan producing highly enriched uranium would sound alarm bells. Until now, Japan has only produced low enriched uranium for power reactors. Higher levels of enrichment would sharpen proliferation concerns. And it would create new challenges for Japan in finding a supplier of uranium source material willing to allow its processing for submarine reactor use.

South Korea, on the other hand, has built its nuclear industry over the last 50 years under a co-operation agreement with the US which precludes it establishing an enrichment facility. Without a change in US policy, South Korea would, like Australia, be dependent on the US for its submarine fuel.

The nuclear submarine community

Nuclear-propelled submarines have hitherto been the preserve of nuclear armed states – China, France, Russia, UK and US. India is joining the club in collaboration with Russia. North Korea too is acquiring the capability, though has a long way to go.

In addition, Brazil has a long established but slow moving acquisition program. Canada had plans in the 1980s but then abandoned the option as too politically difficult and too expensive.

AUKUS was an about-turn in Washington’s attitude to sharing its nuclear propulsion technology. Previous probings by Australian officials in Washington had received a polite but firm rejection – Admiral Rickover’s crown jewels had been shared with the UK but could not be shared more widely, especially to a country without advanced nuclear infrastructure and experience.

This conferred a very special position on Australia among US allies. That honour now looks set to be shared with others, though the details of the US technologies to be made made available to South Korea (and presumably Japan) are still far from clear.

Implications for the Asia-Pacific

The wider adoption of nuclear submarine propulsion was inevitable given the strategic context. South Korea and Japan both face far greater and more proximate security challenges than Australia. And they both offer far greater scope for economic and technology benefit to the US.

On the other hand, Australia’s argument was based on the need for our submarines to travel very long distances to reach anticipated strategic hotspots. For use near shore and in confined seas, conventional submarine propulsion probably remains the best choice. South Korea and Japan will, no doubt, continue to deploy conventional powered submarines in tandem with nuclear powered boats – an option that Australia will not be able to afford.

The wider adoption of nuclear propulsion will affect future US strategic engagement in the region. It will also add to the “nuclear latency” of two key regional powers: how close they are to being able to make, but also deliver, nuclear weapons should they ever decide to do so.

China has so far reacted cautiously, unlike its initial shrill response to the AUKUS submarine announcement. A long bow, but might nuclear submarine proliferation trigger the urgently needed engagement of China in top level nuclear arms reduction talks? The US has been pressing for this, and Trump’s threat to return to nuclear testing could also be the needed spark.

Benefit for Australia?

For Australia, Korean investment in shipbuilding in the US might relieve pressure on the US’ existing submarine construction schedule and help secure the promised second-hand AUKUS submarines.

On the other hand, South Korean and Japanese nuclear-powered submarines might offer an alternative for Australia if the AUKUS plan falls at one of the many major hurdles it has yet to clear.

A clear plus for Australia is that the wider adoption of nuclear propulsion technology in Asia-Pacific will help diffuse, if not defuse, criticism of the AUKUS submarine project in the region.

International supervision

Additional countries seeking nuclear propulsion will also broaden the discussion in Vienna at the International Atomic Energy Agency on how the international community can assure itself that nuclear submarine propulsion will not lead to the proliferation of nuclear weapons.

The AUKUS submarine requirements have been the subject of intense interest at the IAEA for the last four years as negotiations progressed on the technical safeguards arrangements for the nuclear fuel. Australia has committed to ensuring that the AUKUS verification deal “sets the highest nonproliferation standard whilst protecting classified information”.

South Korea (and Japan) will bring unique requirements to Vienna depending on fuel choice, reactor design and confidentiality requirements. But Australian negotiators will now be able to share the burden of those negotiations with two other countries which have traditionally been like-minded on nuclear nonproliferation.

The key is creating a regime that is widely supported, particularly in the Asia-Pacific, and allows no pathway from nuclear propulsion to nuclear weapons.

The views expressed in this article may or may not reflect those of Pearls and Irritations.