The U.S., South Korea, and Japan summit at Camp David on August 18 fortified trilateral security coordination against the North Korean and Chinese threats, and established plans for greater economic collaboration. Thanks to a historic breakthrough in ties between Japan and South Korea, the three countries are now more closely aligned than ever in their strategic policies, aided by convergence in shared principles and perceptions of common threats. The extensive security agreements reached at Camp David, however, will require greater U.S. commitment to improving its military posture in the Indo–Pacific to offset Chinese and North Korean capabilities advancements.

The summitREF with U.S. President Joe Biden, South Korean President Yoon Suk Yeol, and Japanese Prime Minister Fumio Kishida was historic: It was the first independent summit among the three countries. The summit was a recognition of the critical importance of the U.S. alliances with South Korea and Japan in countering common security challenges in the Indo–Pacific. The meeting was also a powerful affirmation of the remarkable progress that Seoul and Tokyo have made in the past year to overcome contentious historic issues.

Last year, Washington, Seoul, and Tokyo restarted trilateral military exercises which, along with the reinstatement of large-scale U.S.–South Korean exercises, will increase allied deterrence capabilities.

This past March, President Yoon took a courageous and politically risky step to resolve the sensitive issue of wartime forced labor with Tokyo,REF to cut the Gordian knot that had been poisoning bilateral ties. As a result of Yoon’s endeavor, South Korea and Japan resumed long-stalled security, diplomatic, economic, and trade cooperation.

Seoul restored its commitment to its bilateral General Security of Military Information Agreement (GSOMIA) with Tokyo, which Yoon’s predecessor had downgraded and threatened to abrogate. Both sides removed trade restrictions imposed in response to deteriorating relations. Last fall, U.S., South Korean, and Japanese leaders agreed to real-time exchange of information on North Korean missile launches.REF

Establishing Camp David Principles

During the Camp David summit, the U.S., South Korea, and Japan committed to an extensive list of initiatives for institutionalizing trilateral security progress and creating a framework for greater cooperation against the North Korean and Chinese threats.REF The three leaders will meet annually, as well as the secretaries and ministers of foreign policy, defense, commerce, and industry and national security advisors. Working-level meetings will ensure implementation of trilateral initiatives.

The three countries agreed to a structured multi-year plan of annual, named, large-scale multi-domain combined military exercises near the Korean Peninsula. In the past, trilateral military exercises were often an ad hoc response to a North Korean provocation rather than part of a regular schedule.REF By the end of 2023, the three countries will activate a new mechanism for exchanging information on North Korean missile launches in real time, which will improve cooperation on ballistic missile defense.

The leaders also committed to greater intelligence sharing, though likely restricted to North Korean threats; greater cooperation on combating cyberthreats; and enhanced economic collaboration, particularly in safeguarding supply chains for key industries.

A senior South Korean official depicted the summit as establishing a “key framework” for a Northeast Asia security cooperative body which, in turn, will strengthen policy coordination with members of the Association of Southeast Asian Nations (ASEAN) and Pacific countries.REF The leaders pledged to develop a maritime security mechanism to synchronize trilateral capacity building in Southeast Asia and Pacific Island nations.

A Bridge Too Far. While the Camp David summit resulted in comprehensive agreement on a range of security, economic, and technological initiatives, it still fell short of some initial U.S. goals. Washington had hoped to expand the recently created bilateral Nuclear Consultative Group between the U.S. and South KoreaREF to include Japan. Doing so, Washington believes, would strengthen the U.S. extended deterrence guarantee to both allies and enhance trilateral contingency planning for a Korean crisis, including nuclear-use scenarios.

However, both allies were reticent. Seoul did not want a perceived dilution of Yoon’s landmark achievement at the April summit in Washington in which South Korea gained greater unilateral access to U.S. nuclear decision-making. Tokyo worried that similar involvement in nuclear planning might go beyond formal legal restrictions or at least political constraints.REF

Challenges Remain. The biggest impediment to further progress will remain the deep-seated Korean animosities from Japan’s brutal colonial and wartime occupation of the Korean Peninsula. Yoon faces fierce criticism by the South Korean populace for being supposedly overly conciliatory to Japan. This could constrain Yoon’s maneuverability for further bilateral coordination, particularly if his ruling party does poorly in April 2024 national legislative elections. The next South Korean administration could abrogate Yoon’s initiatives, as when President Moon Jae-in undermined the 2015 bilateral “comfort women”REF accord with Japan which had been negotiated by his predecessor.

Japanese Prime Minister Kishida also faces nationalist resistance to additional concessions that could buttress Yoon’s political standing. Tokyo has declared that all outstanding historic issues were resolved in the 1965 treaty establishing formal diplomatic relations. Both Yoon and Kishida face very low public approval ratings.

South Korea and Japan also differ in their priorities on regional security threats. Seoul remains focused on the existential North Korean threat looming on the other side of its border while Tokyo is increasingly alarmed by Chinese coercive actions in the East China Sea and against Taiwan.

Washington will remain hampered in its ability to support the new security initiatives by continually underfunded defense requirements. The Heritage Foundation’s 2023 Index of Military StrengthREF assesses the U.S. military as “weak” overall, and as challenged to provide sufficient combat power for a conflict with a peer competitor. The Indo–Pacific theater is a heavily naval and air power domain, but the U.S. is not well positioned. The Index assesses that the Navy needs 400 ships to meet its global demand, but it only has 298 ships, with further declines likely. The Air Force also struggles with capacity issues, lacking the numbers of fighters it needs, in addition to serious pilot training and readiness issues. The Biden Administration has not built a military that is strong enough to fully support the needs in the Indo–Pacific.

What Washington, South Korea, and Japan Should Do

Although South Korea and Japan are unlikely to entertain any formal military alliance for the foreseeable future, the Biden Administration should continue its behind-the-scenes efforts to facilitate bilateral rapprochement. An enhanced framework of operating principles and procedures would enable greater allied cooperation against rapidly growing regional threats.

The Administration should:

Affirm the Importance of Trilateral Security Cooperation. Washington should encourage President Yoon to continue his efforts to improve bilateral relations and expand military coordination with Japan. Doing so will require continued strategic messaging to overcome deep-seated South Korean resistance to engaging with its former occupier. Highlighting the necessity of coordinated allied responses to common security threats, as well as the economic benefits of improved bilateral trade relations, may help to overcome domestic opposition. Similarly, the U.S. should urge Prime Minister Kashida to undertake greater reciprocal measures to enhance South Korean public support for bilateral rapprochement, such as persuading the Japanese business community to make donations directly to the forced-labor compensation fund.

Continue U.S. Measures to Strengthen Extended Deterrence. The viability of the U.S. extended-deterrence guarantee requires credible capabilities, unquestioned commitment, and convincing opponents and allies of that resolve. To augment deterrence against the growing North Korean threat and enhance reassurance to America’s allies, Washington must implement a comprehensive strategy of enhancing nuclear strategy coordination with its allies, augmenting allied conventional military capabilities, and improving trilateral security coordination with Seoul and Tokyo.

The U.S., South Korea, and Japan should:

Augment the Size, Frequency, and Type of Combined U.S., South Korean, and Japanese Military Exercises. The three nations should consider a return to pre-2018 training levels as a minimum requirement for future training schedules. Given the escalating growth in North Korean nuclear and missile forces, Washington should confer with Seoul and Tokyo on a training regimen that includes all military services and goes beyond ballistic missile defense and anti-submarine exercises to include air and ground forces.

In light of lingering historic sensitivities, the three militaries can also engage with other nations during multilateral exercises elsewhere in the Indo–Pacific, developing skills and coordination that could be applied to contingencies on the Korean Peninsula.

Enhance Trilateral Missile Defense. The U.S., South Korea, and Japan should operationalize last year’s agreement to share missile-warning data in real time to improve the identification, tracking, and targeting of North Korean missiles. The three nations should establish techniques and procedures to expedite tracking, targeting, and interception of North Koren missiles.

South Korea is developing a multi-layered Korea Air and Missile Defense (KAMD) system against North Korean threats but has refused to integrate it with that of the U.S.–Japanese system due to lingering tensions with Tokyo over Japan’s 1910-to-1945 occupation of the Korean Peninsula. Having all three nations’ missile defense radars and interceptors working in a coordinated, integrated manner would improve the security of South Korea and Japan as well as U.S. forces in the region.

Expand Trilateral Security Coordination for Regional Contingencies. Trilateral planning and cooperation on Taiwan contingencies would be beneficial to all three nations. However, South Korea has been extremely reluctant to discuss its potential involvement and even criticized U.S. military officials when they publicly broached the topic. The U.S. should privately engage with Japan and South Korea to develop military plans for responding to simultaneous Taiwan and North Korea scenarios.

The Administration and Congress should:

Work Together to Prioritize Defense Dollars for Building Lethality. Congress should look carefully at potential defense savings and efficiencies as it seeks to increase the funding of warfighting capabilities and decrease the amount spent on non-defense matters and inefficiencies. A joint project by The Heritage Foundation and the American Enterprise InstituteREF identified an extensive list of recommendations to wean the Pentagon from wasteful spending to free up funds for more directly countering growing security threats, including in the Indo–Pacific region.

Conclusion

Last year, South Korea and Japan published national security strategies and other security documents that were closely aligned with those of the United States. The three countries must not squander the opportunity to build on already impressive gains in trilateral security coordination.

Navigating the shoals of contentious historic issues and conflicting priorities of America’s Northeast Asian allies is a difficult challenge. But the U.S. is stronger when working in concert with like-minded democracies in the region. As such, Washington must lead the way in organizing allies and partners to deter and defeat the increasingly dire North Korean and Chinese threats.

Bruce Klingner is Senior Research Fellow in the Asian Studies Center at The Heritage Foundation.