Features | Security | East Asia

Promise and Perils for the Japan-South Korea-US Trilateral in 2023

Aside from longstanding historical issues, the three countries will face challenges in sustaining coordination on North Korea and China policy. 

Promise and Perils for the Japan-South Korea-US Trilateral in 2023

South Korean President Yoon Suk Yeol (left), U.S. President Joe Biden (center), and Japanese Prime Minister Kishida Fumio (right) hold a trilateral summit on the sidelines of the NATO Summit in Madrid, Spain, June 29, 2022

Credit: South Korean Presidential Office

The trilateral relationship between Japan, South Korea, and the United States experienced dramatic improvements in 2022, fueled by a major uptick in North Korean provocations and the election of South Korean President Yoon Suk-yeol, who pledged to improve Korea-Japan bilateral relations.

Since May 2022, the three countries have held more than two dozen high-level meetings, including trilateral leaders’ meetings held on the sidelines of the NATO Summit in June 2022 and the East Asia Summit in November 2022. Most notably, the November 2022 Phnom Penh Statement on U.S.- Japan–Republic of Korea Trilateral Partnership for the Indo-Pacific represented a significant new milestone for trilateral relations by expanding the geographic scope and function of trilateral cooperation to cover a wide range of issues beyond North Korean threats.

Although the three leaders seek to implement the Phnom Penh statement and deepen trilateral cooperation this year, they will be confronted by several obstacles at home and abroad. As usual, historical antagonism and domestic politics in Japan-South Korea relations loom in the background. Additionally, however, three challenges for trilateral cooperation come to light in 2023: sustaining coordination on North Korea policy, tightening economic security cooperation, and calibrating divergent perspectives on China policies.

Stopping North Korean Aggression

The escalation in North Korean threats, including a record-breaking number of North Korean missiles fired in 2022 (over 100 by some accounts), has been the biggest impetus in boosting Japan-South Korea-U.S. trilateral cooperation. On one occasion, North Korea fired 23 missiles near the inter-Korea border in a single day, followed by an intercontinental ballistic missile test (ICBM) the next day.

In response to North Korean missile tests, Seoul, Washington, and Tokyo have closely coordinated their response to prevent North Korea from exploiting potential divisions among allies. In one of the first trilateral meetings to take place after Yoon’s inauguration, South Korean Vice Foreign Minister Cho Hyun-dong, U.S. Deputy Secretary of State Wendy Sherman, and Japanese Vice Foreign Minister Mori Takeo set the tone for trilateral cooperation by strongly condemning North Korea’s ballistic missile tests and reaffirming U.S. commitment to extended deterrence in Northeast Asia.

The three countries also resumed joint military exercises that had been mostly suspended since 2017. Exercises included a trilateral ballistic missile drill off the coast of Hawaii in August 2022, and joint anti-submarine warfare exercises in international waters off the East Sea/Sea of Japan the following month.

North Korean threats will continue to be the glue that helps keep trilateral relations intact. However, South Korea’s effort to push for greater nuclear planning and sharing to increase the credibility of U.S. extended deterrence, and Japan’s call for long-range strike capabilities in its new National Security Strategy, bring new challenges to bear in mind. Conversations related to U.S. extended deterrence and nuclear policy on the Korean Peninsula will carry implications for Japan’s national defense. It would be difficult for Washington to include Seoul, but not Tokyo, in any nuclear sharing arrangement aimed at deterring and defending against a North Korean nuclear attack.

Likewise, Japanese counterstrike capabilities, which in theory parallel South Korea’s “kill chain” concept of preemptively striking North Korean targets, may also raise concerns in Seoul. Some South Korean experts have advised the Yoon government to discuss with Washington how the United States can prevent Japan from executing an attack on North Korea without prior South Korean consent. The three governments will need to further discuss the implications of Japan’s shifting defense posture for the Korean Peninsula and the Indo-Pacific region.

Coordinating Supply Chains and Economic Security 

In 2022, the United States announced new tools and mechanisms to address economic security issues, such as a supply chain shortage early alert system. In that vein, Washington, Seoul, and Tokyo pledged to launch an economic security dialogue to address issues related to critical and emerging technologies, supply chains, and data transparency among others. Coordination between South Korea and Japan will be essential given the importance of Korean and Japanese firms in the semiconductor and battery supply chain ecosystem.

But two problems will need to be addressed to strengthen trilateral economic security cooperation. First, existing Japanese export controls on chemicals used by South Korean semiconductor companies, and the decision by both countries to remove the other from their respective “whitelist” of preferred trading partners in 2019 hinder the two countries from building more robust economic ties in an era of greater China-U.S. competition. While export controls have not severely impacted South Korea’s semiconductor industry, they hinder allies from seeking greater coordination on economic security and undermine the spirit of trilateral cooperation.

Second, trilateral cooperation on economic security will require greater clarity from Washington on its use of export controls related to the transfer of advanced computing chips and chip-making equipment to China. These controls may soon extend to other areas such as artificial intelligence, biotechnology, and quantum computing. Although the United States has granted South Korean companies a one-year extension before imposing export controls, Seoul and Tokyo may find it difficult to follow Washington’s lead given the high costs to their own technology industry and the risk of economic retaliation from Beijing. More generally, the Biden administration’s weaponization of economic interdependence runs contrary to the idea of a more open economic order, an approach Japan continues to pursue in its leadership of the Comprehensive and Progressive Agreement for Trans-Pacific Partnership.

Calibrating China Policies

Finally, different perceptions and policy divergences on China among the three countries may weaken the unity of trilateral cooperation, which to date, has focused mostly on the North Korea threat.

Japan has developed stronger rhetoric and taken bolder action in response to growing Chinese influence and assertiveness. For instance, in its recent National Security Strategy, Tokyo pledged to “strongly oppose” China’s attempts to change the status quo and is expanding its military, cyber, and space capabilities.

In contrast, Seoul has adopted a more conciliatory tone toward Beijing, in part to preserve its economic relationship with China. In its recently released Indo-Pacific Strategy, the Yoon administration emphasized inclusivity, specifically naming China as a “key partner for achieving prosperity and peace in the Indo-Pacific.”

Meanwhile, the Biden administration has made outcompeting rivals (i.e. China), a central theme in its National Security Strategy. Throughout 2022, the U.S. Congress and Biden administration tightened export and technology controls against China and encouraged its allies to follow suit. The United States also positioned itself as a vocal defender of freedom of the seas in the Indo-Pacific along with promoting democracy and human rights in Hong Kong and Xinjiang, respectively.

Trilateral policy differences on China also mirror the three countries’ stances on Taiwan. Japan has been more vocal in its support for Taiwan’s defense in the event of a contingency, whereas South Korea has shied away from making direct public commitments beyond calling for “peace and stability” in the Taiwan Strait. Moving forward, however, Tokyo and Seoul may both need to calibrate their positions and begin conversations with Washington as the United States steadily increases military and political support for Taipei through defense cooperation and high-level official visits.

The expansion of trilateral coordination from a focus on North Korean threats and Northeast Asia security to include broader Indo-Pacific issues signals new-found momentum in the Japan-South Korea-U.S. trilateral relationship. Strides in 2022 revealed how productive unity can be when addressing North Korean threats and preserving a platform for coordinating on critical regional priorities. Despite challenges in the new year ranging from North Korea to economic cooperation to divergences on China policy, strengthening and expanding relations must be the objective in pursuing national interests in the Indo-Pacific and beyond.