On July 13, nearly five months in to Russia’s unprovoked assault on Ukraine, the Pentagon announced that the United States had successfully tested two hypersonic missiles. Following a string of highly publicized failures, the successful test was an important step toward catching up in an area of weapons development in which China and Russia have been pulling ahead. Just seven weeks later, amid rising tensions with China, Japan reported its largest-ever increase in defense spending, including funds explicitly earmarked for hypersonic weapons research. Tokyo’s announcement was a pointed reminder that Japan’s technological and security policies and ambitions are increasingly aligned with those of Australia, the United Kingdom, and the United States, the three long-standing allies that comprise the trilateral security pact known as AUKUS.

When AUKUS was formed in September 2021, it was with the initial limited goal of equipping Australia with nuclear-powered submarines. But with that program underway and the AUKUS countries planning further collaboration on the cutting edge of military innovation, it is time to consider expanding the trilateral partnership to include Japan. Tokyo is exceptionally well equipped to help Canberra, London, and Washington develop critical defense technologies and bolster stability in Asia. The transition from AUKUS to JAUKUS would represent the natural evolution of the group.

WHY TOKYO WAS EXCLUDED BEFORE

Japan was not brought into AUKUS at the outset for several reasons. First, Canberra, London, and Washington have close and long-standing security partnerships, having fought side by side in every major conflict since World War I. Japan, by contrast, long restrained by post–World War II restrictions on its use of military force, has not had the opportunity to develop multilateral military relationships to the same extent as other U.S. allies. Those restrictions have also prevented Japan from engaging in significant defense-industrial cooperation with other countries, so Tokyo lacks experience in the kind of collaboration that forms the core of the AUKUS partnership. Moreover, since AUKUS was formed with the original goal of coproducing eight nuclear-powered attack submarines for Australia, Japan—which is well known for its stance against military nuclear technology—did not seem like a natural participant.

These basic facts have changed little in the 13 months since AUKUS was formed. But Japan’s unique status—as the world’s third-largest economy, the most influential liberal democracy in the Indo-Pacific, and Washington’s key Asian ally—makes a strong case for its inclusion, especially as AUKUS plans its next phase of cooperation.

Japan began to assert its leadership in the Indo-Pacific under Shinzo Abe, who served as Japan’s prime minister from 2012 to 2020 and was assassinated during a July 2022 campaign rally. The trend has continued under Abe’s successor, Prime Minister Fumio Kishida. After the United States’ abrupt withdrawal from the Trans-Pacific Partnership in 2017, for example, swift Japanese diplomacy saved the 11-member free-trade pact. Japan has also shown its strength in maritime security, thwarting China’s decade-long attempt to gain control of the Senkaku Islands (known in China as the Diaoyu Islands), which would put freedom of navigation in the East China Sea at risk. Like Abe, Kishida has argued forcefully that preventing a Chinese takeover of Taiwan is critical to security and stability in East Asia. Perhaps most notably, Japan, along with Australia, India, and the United States, is one of the four core members of the Quadrilateral Security Dialogue, a group often referred to as the Quad. It was Abe, in fact, who first articulated the Quad’s vision of a “free and open Indo-Pacific.”

But the Quad, despite laudable progress on cybersecurity, emerging technologies, and outer space, has split on the question of opposing Russia’s invasion of Ukraine, with India refusing to join the other members in sanctioning or condemning Russia. AUKUS, meanwhile, has prioritized unity and maintained close cooperation amid Russia’s war in Ukraine and China’s increased military activity around Taiwan in the wake of U.S. House Speaker Nancy Pelosi’s August visit to the island. As China and Russia, along with Iran and North Korea, increasingly undermine global stability, liberal countries feel pressured to band together even more closely. Regional groupings such as NATO and AUKUS are becoming more central to allied security planning.

AUKUS EXPANDS ITS REMIT

If the nuclear submarine deal did not fit Japan’s security interests, April’s announcement of the next steps AUKUS cooperation will take—namely, an ambitious expansion into hypersonic weapons—more closely mirrors Tokyo’s priorities. Spurred by recent Chinese and Russian successes developing hypersonic weapons that essentially negate any missile defense systems, U.S. President Joe Biden’s administration has pledged to work with Australia and the United Kingdom to fast-track the development of nuclear-capable hypersonic vehicles.

AUKUS has also announced plans to develop counter-hypersonic technology and electronic warfare. Its members reiterated their intent to develop military-related aspects of quantum technology for “positioning, navigation, and timing” and to develop artificial intelligence capable of “improving the speed and precision of decision-making processes to maintain a capability edge and defend against AI-enabled threats.” Taken together, these expanded AUKUS initiatives make it clear that Washington is intent on deepening hard-power partnerships with its key allies in the face of China’s continued military modernization.

Thanks to recent changes in its security policies, Japan could contribute significantly in all these areas. Beginning in 2006, during Abe’s brief first term as premier, Japan began to publicly question its long-standing pacifism. The shift accelerated when Yoshihiko Noda, who served as prime minister from 2011 to 2012, released strategic policy papers that identified protecting Japan’s far-flung southern islands from China as a critical national security priority.

Once Abe returned to power, he formed Japan’s National Security Council, consistently increased the defense budget, and removed impediments to Japan’s abilities to act in collective self-defense and sell arms abroad. The modernization of Japan’s military proceeded apace in these years, with Tokyo agreeing to purchase F-35 fighter jets (becoming the biggest purchaser after the United States) and building a new class of large helicopter carriers that could be converted to F-35B aircraft carriers.

Bringing Japan into AUKUS could bolster U.S. and Australian security cooperation in critical Indo-Pacific sea-lanes.

At the same time, Abe championed the Quad and increased Japan’s cooperation with Southeast Asian nations, India, and NATO. In the months before his assassination, Abe openly called on Washington to commit to defending Taiwan from a Chinese invasion and shocked his country by musing about whether Japan should host U.S. tactical nuclear weapons. On July 18, Japan and the United Kingdom announced that they are collaborating with Italy to develop a next-generation fighter jet. All this has combined to make Japan an increasingly important security player in Asia and beyond. 

Including Japan in AUKUS is a natural next step that could bolster U.S. and Australian maritime security cooperation in critical Indo-Pacific sea-lanes, where the United Kingdom has only an occasional presence. Although the Japan Maritime Self-Defense Force (JMSDF) does not currently have nuclear-powered submarines, its conventional submarine fleet is among the world’s best, and it can contribute leading nonnuclear technology to the Australian submarine deal, as well as slowly prepare the way for Japan to move toward adopting nuclear subs. Further, with China’s military outpacing all others, JAUKUS could cooperate on next-generation autonomous military technology and militarized cyber-operations, areas in which Japan’s high-tech capabilities can complement those of the United States.

Just as important, Japan remains a leader in supercomputing and currently has the world’s most powerful supercomputer, the Fugaku, made by Fujitsu. JAUKUS could take the global lead on quantum development and research on artificial intelligence and machine learning, creating a powerful alliance of high-tech liberal democracies that can guide the development of next-generation applications. To spark further collaboration on these goals, JAUKUS could also develop a STEM-focused fellowship of the kind now being started by the Quad and run by Schmidt Futures.

AUKUS’s plans to supply Australia with up to eight nuclear-powered attack submarines would link the Royal Australian Navy more closely with the U.S. and British navies and allow it to undertake extended deployments and project power throughout the critical sea-lanes and littoral waters of Southeast Asia and the Indian Ocean. These capacities would mesh well with Japan’s extensive submarine capabilities in the East China Sea and areas of the western Pacific Ocean, as well as with the JMSDF’s cooperation with the U.S. Navy on sea-lane security in Northeast Asia. Perhaps more important, the U.S. admiral in charge of the Navy’s submarine program recently warned that building nuclear submarines for Australia will throw American production schedules into disarray. As a major submarine builder, Japan may be able to help with production and gain experience with nuclear submarine development.

SUPPORT FOR JAPAN'S NEW ROLE

Although none of the countries in AUKUS have publicly acknowledged any discussion of Japan’s inclusion in the alliance, some officials and former officials have expressed support for the move. Former U.S. Deputy Assistant Secretary of Defense Elbridge Colby has described it as a good way to incentivize greater Japanese defense efforts as well as gain the advantages of “superb Japanese technology and industry”. Tom Tugendhat, a member of the British Conservative Party who was chair of the House of Commons Foreign Affairs Committee and now serves as minister of state for security, has said that “having Japan join AUKUS would be a fantastic boost to the partnership and deepen the alliance that should become the building block of our future security in the region.”

John Lee, the former senior national security adviser to Australia’s foreign minister, has stated that in Canberra, “there would be strong political and bureaucratic support for Japan’s involvement if not inclusion.” Yet Lee also warned that Australians might hesitate to accelerate Japan’s inclusion in the immediate term.” The legacy of Japan’s noninvolvement in multilateral security cooperation remains a concern, Lee suggested, arguing that AUKUS would “want to ensure complete Japanese alignment regarding the protocols and procedures to safeguard military technology and related intelligence protocols and procedures.” But Tokyo’s defense agreements with Canberra and London, not to mention its close alliance with the United States, have already begun to allay such concerns. Including Japan in AUKUS would further strengthen the country’s relations with its closest political partners and revitalize cooperation between liberal partners in the Indo-Pacific.

The Japanese people themselves have not yet reached consensus on the issue. One official not authorized to speak publicly said that there would be widespread interest in Tokyo in working with the AUKUS countries as a “trusted and valued partner.” As to the question of formally joining what started as a nuclear-technology deal (for submarines), the official noted that the expansion of AUKUS’s focus to include quantum computing and cyber-activities makes it an easier sell to the Japanese public.

Other senior Japanese officials are warier, believing that Tokyo should focus first on “NATO + 4” (Australia, Japan, New Zealand, and South Korea) to deepen cooperation with a broader range of Asian and European nations. In June, Kishida became the first Japanese leader to attend a NATO summit, and many officials believe that Japan can more easily increase its security cooperation in a broad multilateral grouping such as NATO than in a narrower initiative such as AUKUS. The priority, these officials noted in conversations with me, would be the Quad, NATO, then AUKUS, all of which naturally come after the U.S.-Japanese alliance, which remains the cornerstone of Tokyo’s security planning.

For Australia, the United Kingdom, and the United States, the pluses of including Japan in AUKUS outweigh the minuses. Japan’s desire to join AUKUS will likely grow as regional tensions mount. Overlapping, even redundant, security groupings can be seen as a net positive only in an environment of increasing uncertainty. Although it may take time to achieve a consensus in Tokyo on joining and to iron out the contours of Japan’s participation, creating a JAUKUS group would bolster the U.S.-Japanese alliance, deepen Japan’s relations with Australia and the United Kingdom, and complement Quad cooperation on global health, infrastructure, climate, and cultural exchanges.

Russia’s invasion of Ukraine has refocused national security on traditional hard-power capabilities, and China’s pushback on Taiwan after Pelosi’s visit shows the continuing fragility of Indo-Pacific stability. Although the security threat in Europe may absorb Washington in the short term, the need to maintain order in the Indo-Pacific is ultimately a far greater challenge. AUKUS was formed in recognition of that fact, and Japan’s inclusion would make the group an even more critical player in regional security.

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