March 21, 2024

Forging a New Era of U.S.-Japan-South Korea Trilateral Cooperation

The Key to a Stable, Secure Indo-Pacific

Executive Summary

In August 2023, the leaders of Japan, the Republic of Korea (ROK), and the United States met for an unprecedented in-person summit at Camp David to expand and deepen trilateral relations. The meeting resulted in a comprehensive joint statement, “The Spirit of Camp David,” which commits the three nations to increasing the frequency of consultations between their leaders and senior diplomatic, economic, and security officials; raising the tempo and sophistication of their joint military exercises; taking new initiatives such as sharing sensitive missile warning data on North Korea in real time; collaborating on economic security measures and the protection of emerging technologies; and working together to stabilize global supply chains by launching a pilot early warning system. The Biden administration deserves credit for coordinating this watershed moment in trilateral relations, but South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida were responsible for the bilateral rapprochement that laid the foundation for renewed trilateral relations.

A major contributing factor to Japan and South Korea’s interest in improving defense ties with each other and trilaterally with the United States is the intensifying nuclear and missile threats from North Korea. Washington, Seoul, and Tokyo have laid out an ambitious defense cooperation agenda, including reviving trilateral maritime cooperation, initiating trilateral aerial cooperation for the first time, and bringing online a real-time trilateral data sharing system for tracking North Korean missile launches.

The three countries are poised to expand their cooperation across a range of issues and within other minilateral and multilateral settings. This includes the United Nations (UN), where, as of January 2024, both Japan and South Korea serve as non-permanent members of the Security Council—an overlap with the United States, a permanent member, which has not taken place in 27 years. Japan and South Korea are already coordinating their diplomatic activities in response to the Israel-Hamas conflict in the Middle East, demonstrating the potential for trilateral collaboration outside the Indo-Pacific region.

There is both opportunity and appetite to enhance trilateral cooperation across a range of critical technology areas, namely quantum, biotechnology, and cybersecurity.

Economic and technological competition with China also is driving the current push to cooperate trilaterally. Japan-ROK rapprochement has ended the trade dispute between Seoul and Tokyo, and the three partners are now deepening cooperation on economic security to secure supply chains for semiconductors, electric vehicle batteries, and critical minerals. President Yoon and Prime Minister Kishida have encouraged industry cooperation, and all three capitals are now in discussions to further cooperation in novel technology areas.

There is both opportunity and appetite to enhance trilateral cooperation across a range of critical technology areas, namely quantum, biotechnology, and cybersecurity. The three nations already have largely complementary national quantum technology strategies, and there are opportunities to align resources to further quantum information science and technology (QIST) research and development and to harness the technology’s economic potential together. All three countries are interested in strengthening their respective biotechnology sectors as well as addressing cybersecurity challenges, especially related to North Korea and its funding for nuclear and missile programs.

Despite the immediate prospects for strengthening trilateral cooperation, there are several obstacles to sustaining meaningful collaboration over the long term. A change in national leadership in Tokyo, Seoul, or Washington could halt the partnership, as it is closely tied to the personal foreign policy agendas of all three leaders. Likewise, institutionalizing trilateral cooperation, regardless of leadership change, will be challenging in the long run. The Indo-Pacific security environment is increasingly severe, and varying perceptions among the three nations of threats posed by China, Russia, and North Korea could lead to cracks in trilateral relations. Similarly, policymakers in all three capitals will need to carefully balance economic security with nationalist or protectionist trade policies to sustain support for trilateral economic and technology cooperation.

The large number of both opportunities and challenges facing the trilateral partnership means leaders in all three capitals have difficult decisions to make to sustain the momentum of the partnership. It is imperative for Japan, South Korea, and the United States to take the initiative and seize the low-hanging opportunities to further institutionalize and strengthen the ties with each other. In this context, U.S. policymakers should:

  • Continue to press for expanded trilateral cooperation within the UN. Both Japan and South Korea are non-permanent members of the UN Security Council (UNSC) at the same time for the first time in 27 years. Using formal, multilateral forums such as the UNSC for trilateral cooperation can help reinforce progress made elsewhere and provides a dedicated means to align on issues the three parties have agreed to tackle together.
  • Create an interagency working group to identify opportunities and gaps in coordination among different minilateral groups, including the U.S.- Japan-ROK trilateral, the Quad, the “Chip 4,” and the U.S.-Australia-Japan Trilateral Security Dialogue. In addition to improving diplomatic efficiency, encouraging greater coordination among the various minilaterals can provide opportunities for Japan and South Korea to deepen their security relationships with like-minded partners, contributing to the development of a networked security architecture aligned with U.S. priorities.
  • Encourage trilateral cooperation beyond the Indo-Pacific. Japan and South Korea have coordinated some diplomatic activities in response to the Israel-Hamas conflict. The United States should take advantage of this progress and encourage trilateral cooperation in other regional or functional areas of mutual interest, such as energy security in the Middle East or Russia’s war in Ukraine.
  • Increase trilateral intelligence sharing to enhance collective maritime domain awareness. The three countries should begin strengthening intelligence sharing beyond the North Korean missile threat by strengthening cooperation on maritime intelligence, surveillance, and reconnaissance.
  • Enhance trilateral contingency planning, especially evacuation of civilians. All three countries have an incentive to work together in evacuating civilians in the event of a regional contingency involving Taiwan. Modernizing alliance command and control structures can further enhance trilateral contingency planning and interoperability.
  • Plan trilateral defense exercises that expand beyond traditional domains to include cyber and space. China, Russia, and North Korea continue to invest in cyber and space capabilities. U.S. defense planners should consider trilateral exercises outside of traditional domains, such as joint space domain awareness or active cyber defense.
  • Encourage trilateral cooperation to further QIST research and development and harness the technology’s economic potential. The three states already have largely complementary national quantum technology strategies and capabilities, with the United States leading in quantum sensing, Japan excelling in quantum communications, and South Korea advancing in the field of quantum computing.
  • Launch a trilateral biotech industry working group and begin negotiations on a trilateral biotechnology cooperation agreement. The Biden administration should engage more robustly on emerging biotechnology with Japan and South Korea as a key area for strategic advancement.
  • Build consensus both at home and with trilateral counterparts to operationalize the trade pillar of the Indo-Pacific Economic Framework. This is critical to demonstrate the body’s strength—and by extension the United States' strength as an organizing force—to a watchful China.

Introduction

The recent unprecedented trilateral cooperation between Japan, the Republic of Korea (ROK), and the United States under the administrations of Prime Minister Fumio Kishida, President Yoon Suk Yeol, and President Joe Biden is laying a foundation for the three countries to collectively address increasingly critical economic, political, and security challenges in the region. Following a watershed summit at Camp David in August 2023, the trilateral partnership has expanded beyond addressing just the traditional, shared threat posed by North Korea to cover broader security issues in the Indo-Pacific region and beyond. At the summit, the leaders jointly announced their commitment to deepen cooperation and align efforts to promote peace and stability and a rules-based order in the Indo-Pacific region. Following the summit, from mid-August to early December 2023, the three nations met roughly 30 times—averaging nearly one meeting every four days—to operationalize their pledges of closer cooperation. These developments show promise for a new era in trilateral relations that could help address nuclear and missile threats from North Korea and contribute to deterrence, stability, and economic prosperity throughout the Indo-Pacific.

(L-R) South Korean President Yoon Suk Yeol, U.S. President Joe Biden, and Japanese Prime Minister Fumio Kishida walk together to deliver a joint press conference following their historic Camp David summit on August 18, 2023. Among other things, the joint statement called for improved information sharing and increased defense, economic security, and technology cooperation. (Chris Somodevilla via Getty Images)

While the recent momentum in trilateral relations has the potential to fundamentally alter the economic and security landscape of the Indo-Pacific, questions about the political sustainability of the initiative have already emerged. A presidential election in the United States, a ruling party presidential election in Japan, and National Assembly elections in South Korea will occur in 2024, and there is concern that new leadership or shifts in political power dynamics in any of the three nations could lead to the deprioritizing of trilateral ties. Historical frictions in the Japan-ROK bilateral relationship also threaten to disrupt the initiative, especially in South Korea, where public support for improving relations with Japan lags behind Yoon’s personal commitment to moving them forward. The ambitious Camp David agenda will also take time and concerted effort to operationalize, and it could lose momentum and support if there are too many obstacles to its implementation. Finally, external security threats, such as Chinese economic coercion and maritime aggression or burgeoning Russia-North Korea defense and technology cooperation, could also reduce support for the initiative among the South Korean or Japanese public, causing either or both countries to back away from it.

This report examines recent developments driving trilateral relations between the United States, Japan, and South Korea, and assesses the opportunities and challenges facing the future of trilateral cooperation. It then offers policy recommendations for how decisionmakers in Tokyo, Seoul, and Washington can leverage the current momentum of the partnership to further institutionalize trilateral relations, strengthen the durability of the relationship, and build on the Camp David agenda to promote peace and stability in the Indo-Pacific region.

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  1. The White House, “The Spirit of Camp David: Joint Statement of Japan, the Republic of Korea, and the United States,” press release, August 18, 2023, https://www.whitehouse.gov/briefing-room/statements-releases/2023/08/18/the-spirit-of-camp-david-joint-statement-of-japan-the-republic-of-korea-and-the-united-states/.
  2. ラーム・エマニュエル駐日米国大使 [United States Ambassador in Japan Rahm Emanuel] (@USAmbJapan), “Today’s trilateral National Security Meeting in Seoul marks the 30th such gathering since the historical Camp David Principles, averaging nearly one every four days. 2023 has been crucial…” X (formerly Twitter), December 8, 2023, https://twitter.com/USAmbJapan/status/1733310960209986009.

Authors

  • Lisa Curtis

    Senior Fellow and Director, Indo-Pacific Security Program

    Lisa Curtis is a Senior Fellow and Director of the Indo-Pacific Security Program at CNAS. She is a foreign policy and national security expert with over 20 years of service in...

  • Evan Wright

    Research Assistant, Indo-Pacific Security Program

    Evan Wright is a Research Assistant for the Indo-Pacific Security Program at CNAS. He focuses on U.S.-Indo-Pacific relations, East Asian security, and science and technology p...

  • Hannah Kelley

    Research Associate, Technology and National Security Program

    Hannah Kelley is a Research Associate with the Technology and National Security Program at CNAS. Her work focuses on U.S. national technology strategy and international cooper...

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