The question as to whether Japan and South Korea should be invited to join AUKUS, or a similar agreement based on the AUKUS model, has in recent weeks again been garnering attention.
In late August a report from the United Kingdom’s Foreign Affairs Committee recommended to its Parliament that the two technology and defense powerhouses should “be invited to join an AUKUS technological defense cooperation agreement,” or Pillar Two of the pact.
Following on from this, calls for Japan and South Korea’s accession were repeated by Song Seung-jun, head of the Security Strategy Center of the Korea Research Institute for National Strategy (KRINS). Song wrote the pact needs to look beyond its Anglo-Saxon roots, and argued “it is no longer realistic” for the United States to be expected to protect “every corner of the Korean peninsula” on its own.
Soon after, an article from Oxford University’s U.S. Navy fellow, Cmdr. Douglas Robb, proposed a “JROKUS” focused on technology sharing to help the two nations plug U.S. capability gaps by producing guided missile frigates. This followed support for the two nations’ accession from other U.S. Navy officials, including Surface Warfare Officer Jasmin Alsaied’s proposal of an AUKUS+2 relationship to help counter China’s threats to maritime “rules-based norms.”
While interest grows in the U.K. and the U.S. for Japan and South Korea to join, Canberra’s attitude toward the two nations’ accession has hitherto been cool. In a speech hosted by Japan’s Sasakawa Peace Foundation in December last year, Australia’s Minister of Defense and Deputy Prime Minister Richard Marles said that “there’s a chance to involve Japan… and I think that view is shared by both the U.K. and the U.S.” But he added that this should only happen after AUKUS starts “delivering” for its current members. There is little indication that consideration has been given to the accession of South Korea, which was not even mentioned in Canberra’s 2023 Defense Strategic Review (DSR).
But Australia has compelling reasons to put its concerns into perspective and carefully consider inviting Japan and potentially South Korea. These two nations are both best equipped, and likely to be increasingly needed, to help AUKUS achieve the outcomes that motivated Canberra’s own decision to enter the pact.
Retaining the Balance of Power
Arguably the strongest case for Canberra backing Japan and South Korea’s accession into AUKUS is that it would help realize what, according to recent statements from Australia’s foreign and defense ministers, is Australia’s core motivation for signing up to AUKUS – maintaining the “balance of power” between China and the U.S.-led alliance.
Northeast Asia plays the pivotal role in defying strategic gravity. Beijing is a global power but lacks hegemonic influence in its immediate neighborhood. Northeast Asia is not only the locus of the combination of the United States’ locally-based force posture – more than 70,000 U.S. troops and the U.S. Navy’s largest forward-deployed fleet – but Japan and South Korea themselves are two top military powers, whose respective capabilities far exceed Australia’s.
This point was pressed home in a report released earlier this year by the Washington-based Center for Strategic and International Studies. The report was based on wargames simulating a Chinese invasion of Taiwan – a scenario likely to profoundly impact the geopolitical architecture of the Indo-Pacific. Roughly concurring with another recent wargame by Japan’s Sasakawa Peace Foundation, the exercise found that the U.S. alliance could prevail, but that Japan was the “linchpin” because U.S. forward bases there enabled its assets to “effectively participate in the war,” augmented by contributions from Japan’s air force and navy.
While basing rights and direct military contributions were not expected from South Korea, the latter’s role was also essential in the wargame. This is because it is the closest source for the timely redeployment of supplementary U.S. capabilities to Japan, and a buffer protecting Japan’s western flank from a diversionary or concomitant strike from North Korea or other actors (i.e., China or Russia).
Yet the significance of these two nations extends beyond Taiwan. The proximity and size of the 7th Fleet and other U.S. assets based in the region, in addition to the potential for the mobilization of Japan and South Korea’s growing blue water and power projection capacities, are major reasons why China cannot fully count on sustained sea control over its near seas in the immediate future. This makes Beijing currently unable to extend its influence by leveraging de facto control over trade routes traversing the South China Sea – another one of Canberra’s rationales for the AUKUS program.
But perhaps most importantly for Canberra, the strategic gravity of this region, less than 1,000 kilometers from Beijing in the case of Seoul, is what anchors down China’s aspirations for projecting power further afield – including into Australia’s neighborhood.
A key fear motivating AUKUS, and emphasized in the DSR, is the rapid development of long-range weapons. Attacks against Australia can now be launched from areas far beyond those in which Australia’s current navy and air assets could comfortably navigate. While nuclear-powered submarines – the centerpiece of AUKUS – can provide some capacity in this regard, forces based in Northeast Asia would play a complementary role, being both more potent and in closer proximity to the source of these threats.
These forces also help deny China absolute sea control across the seas that the People’s Liberation Army would need to traverse to encroach on Australia’s “inner security arc” – something that nuclear-powered submarines would also prevent. This reality is what makes the recent specter of Chinese bases in Solomon Islands and elsewhere a grave concern to Canberra, but not quite a panic-inducing existential threat.
The point of extending AUKUS to Japan and South Korea is that as Beijing continues its ominous military rise, the balance of power will increasingly rest on those two nations’ capacity to augment the United States’ forward-based force posture. This point was pressed home in January when U.S. Chief of Naval Operations Admiral Mike Gilday said that “a forward-looking relationship” between the U.S., Japan and South Korea “is no longer a luxury but a necessity,” while floating the idea of an AUKUS-like arrangement to equip Japan with nuclear powered submarines.
Technological Balancing
Yet Japan and South Korea are also expected to contribute to the balance of power in another key way: by helping the U.S. alliance network retain the technological lead that underwrites U.S. military supremacy. Outside of kinetic warfare, this same technological prowess contributes to the broader economic, industrial capacity, and technological underpinnings of the democratic world’s systemic power.
Aside from having their own strengths in military technology, both South Korea and Japan have a place in the advanced semiconductor supply chain ecology vital to keeping the United States ahead in the race for arguably the most critical dual use technology. South Korea produces some of the world’s most advanced chips, and Japan is a major supplier of the semiconductor manufacturing equipment that makes their production possible. Both also punch above their weight in other emerging technology R&D and production, and provide alternatives in the advanced manufacturing and emerging technology sectors where China enjoys relative strength vis-à-vis the United States.
In relation to AUKUS Pillar Two specifically, Japan is making major investments in quantum computing, and both Tokyo and Seoul have expressed interest in participating in advanced AI and autonomy projects. In short, a technology-sharing agreement akin to the Pillar Two pact with Japan and South Korea could build on existing exchange conduits and would take the form of mutually beneficial, two-way exchange.
Keeping a Seat at the Table
These security and dual use technology-related strengths are already apparent to Australia’s AUKUS partners. And they have prompted both the United States and the United Kingdom to make pronounced security and technology cooperation pivots toward Japan and South Korea.
Last year two trilateral summit meetings were held between the leaders of Japan, South Korea, and the United States, culminating in the breakthrough summit meeting at the U.S. presidential retreat at Camp David in August, which was touted as the inauguration of a “new era of trilateral relationship” in and beyond these areas. Talk has been matched by action – since February the U.S. has joined Japan and/or South Korea in missile defense drills, bilateral maritime exercises, land-based training drills and joint live fire exercises, submarine visits, and new iterations of large-scale drills, including the Ulchi Freedom Shield Exercise. Both Japan and South Korea have been heavily involved in inbound U.S. investments and “friendshoring” arrangements linked to or inspired by the U.S. CHIPS and Science Act and the Inflation Reduction Act (which focuses on rechargeable batteries and electric vehicles).
The U.K. has followed a similar trajectory. Last June it signed the comprehensive U.K.-South Korea Bilateral Framework for Closer Cooperation, which called for “closer interoperability between our respective Armed Forces and capabilities across all domains.” This was followed up by the inaugural U.K.-South Korea Senior Economic Dialogue, and hastened negotiations on a new trade pact with Seoul aiming to improve the United Kingdom’s “security and resilience.”
This year also saw the signing of a new Japan-U.K. defense agreement, the Japan-U.K. Strategic Economic Policy and Trade Dialogue, the Hiroshima Accord (under which the U.K. will deploy its Carrier Strike Group to the Indo-Pacific in 2025), and the coming into effect of a reciprocal access agreement between the two nation’s defense forces. The U.K. upped its participation in joint security drills, joining infiltration drills with South Korea and the United States, sending Royal Marines to join drills on the peninsula for the first time since the Korean War, and dispatching Royal Air Force assets to Japan to participate in Exercise Mobility Guardian 23.
The strength of these pivots, and the strategic calculi motivating them, are the backdrop against which the U.K. parliamentary committee recommendation for inviting the two nations into AUKUS was formed. If these ties continue to deepen, Canberra will want a seat at any table in which the Asian nations and its AUKUS partners come together. Without doing so, Australia – and perhaps even AUKUS – risks marginalization from the forums where the most important conversations about the U.S.-led alliance take place.
Overcoming Obstacles
There are, of course, valid reasons why an invitation might face impediments. Key among them are risks around secrecy protection.
Neither Japan nor South Korea reaches the trust threshold to join the Five Eyes – unlike other prospective AUKUS members such as New Zealand, which the United States has overtly welcomed. As such, any pact would at best be constrained to a limited “Pillar Four” for the interim period that excludes highly sensitive technologies.
A go-around could be an agreement that focuses on providing technical capacities to mobilize the defense industries of Japan and South Korea to produce platforms where there are capability gaps and a history of technology sharing – similar to that proposed by Douglas Robb. Another option would be different agreements for two-way, complementary cooperation in advanced technologies, which bring the respective R&D strengths of the two nations into play.
In any case, risks of secrets falling into the wrong hands need to be weighed against the opportunity costs of turning the two allies away. On this front, while U.S. Navy voices may know little about the ins and outs of intelligence, their advocacy comes from a clear headed appreciation of the needs and challenges facing U.S. forces in the Indo-Pacific.
Another obstacle for Canberra is its focus on its more immediate neighborhood. Australia has recently pivoted toward Southeast Asia – which Prime Minister Anthony Albanese has called “the world’s next economic powerhouse” and the locus in which Australia’s “economic future lies.” There has been recognition that such a partnership should be marked by “a complete link between… economic relations and national security.” But for this to be realized, before the powers of tomorrow have risen, an environment needs to be retained where they are free to exercise their agency, and not fall into the web of the security-economic nexus of a hegemonic regional power. Northeast Asian states may be facing demographic headwinds with historic low birthrates, but Japan and South Korea have an important role to play in retaining this situation as the premier regional powers of today.
Yet this regional focus in part reflects the problem that Canberra – which, unlike the U.K. or the U.S., has never been a global power – is yet to fully effectuate the shift in strategic mindset its embrace of AUKUS has symbolized. Doing so will require overcoming deep seated anxieties and myopias, and is as much a visceral as an intellectual challenge. Essentially, for Australia to free its grand strategy from the arbitrary divisions of toponomy (such as that between the South and East China Seas) it must negotiate the emphasis on geographical proximity concomitant with the geopolitics of Australia’s older Oceanic power status, and the more expansive, newer geopolitics of trade and security networks and nodes. With disagreements over the fundamental premises of AUKUS still raging in and beyond Canberra, that journey – and a push to invite Japan and South Korea into AUKUS – are some way from fruition.