If we consider Northeast Asia as a weiqi board, the United States and China are making similar moves, attacking each other’s alliance networks to encircle the opponent’s options.
The United States is strengthening trilateral security cooperation with Japan and South Korea while broadening the agenda to encompass economic cooperation. China is endeavouring to leverage its economic advantages to engage Japan and South Korea and mitigate potential security risks from the US-led trilateral partnership.
In April 1999, the United States initiated the Trilateral Coordination and Oversight Group with South Korea and Japan to coordinate efforts in addressing North Korea’s nuclear issue. In November 1999, China, South Korea and Japan met on the sidelines of the ASEAN+3 Summit, initiating the journey towards its own cooperation mechanism.
Both mechanisms stagnated due to a variety of factors, including unresolved legacies between South Korea and Japan, eroding trust caused by China’s aggressive actions, the establishment of multilateral frameworks such as the Six-party Talks and the US shift to unilateralism under former president Donald Trump.
Under US President Joe Biden — an ardent supporter of multilateralism — the US–Japan–South Korea trilateral mechanism has been reinvigorated, becoming a focal point in the US Indo-Pacific Strategy. A ‘new era’ of cooperation has begun since the first Summit of Camp David in August 2023.
China also actively supported the revival of China–Japan–South Korea trilateral cooperation. In May 2024, Chinese Premier Li Qiang, Japanese Prime Minister Fumio Kishida and South Korean President Yoon Suk-Yeol attended the fifth trilateral Summit in Seoul. The move was interpreted as a Chinese attempt to disrupt the growing closeness between the United States, Japan and South Korea.
Deterrence has emerged as the most striking area of US–Japan–South Korea cooperation. According to the Spirit of Camp David joint statement, the United States has reaffirmed its commitment to extended deterrence for Japan and South Korea. This aligns with Japan’s shifting defence posture shown in its 2022 National Security Strategy and may reassure South Korea, which has indicated interest in developing its nuclear arsenal. But the defensive posture could backfire, sending misleading signals that could escalate tensions from North Korea or China.
While there are concerns that the US–Japan–South Korea trilateral might lead to a China–Russia–North Korea axis, this possibility is low. China has reservations about Russia and North Korea’s rapprochement and Beijing also seeks to maintain its international image by playing a mediating role in the Russia–Ukraine conflict, which can consolidate China’s status in the contemporary international order.
Economic factors may serve as a more effective cohesive force for cooperation than security issues. The US–Japan–South Korea agenda emphasises economic cooperation to build resilient supply chains. To deal with ‘economic coercion’, the parties agreed to promote dialogue on economic security. Although no specific subject was mentioned, the implied target is China, which has implemented economic bans and retaliatory measures due to political disagreements with Japan in 2010 and South Korea in 2016.
The China–Japan–South Korea trilateral cooperation also promotes economic cooperation, particularly as China seeks to gain support from Japan and South Korea against US efforts to suppress Chinese high-tech companies. In a joint statement after the trilateral summit meeting in May 2024, the trio agreed to strengthen ‘supply chain cooperation’ and avoid ‘supply chain disruptions’, allegedly referring to US export restrictions on chip-related technologies to China. The absence of security narratives in the joint statement indicates the growing role of economic cooperation between China, Japan and South Korea.
The future of the two trilaterals remains uncertain. It is likely that restarting trilateral cooperation mechanisms would have been unfeasible if President Yoon did not come to power. But his attempts to improve ties with Japan are met with hostility from the opposition party in South Korea due to historical issues.
If Kamala Harris is elected, US foreign policy might build on Biden’s legacy. The scenario would likely differ if Trump returned to the White House. When addressing security issues in Northeast Asia in his previous term, Trump severely undermined relations with Japan and South Korea by disregarding the interests of traditional allies.
In 2019, Trump asked Japan and South Korea to increase their financial contributions to US security guarantees — a demand which would be a considerable obstacle to maintaining Japan and South Korea’s extended deterrence, as committed to in the 2023 Summit. As a result, US–Japan–South Korea cooperation might remain diplomatic and the institutionalisation process could slow down.
Some reports believe that Trump would support tightening relations between the United States, Japan and South Korea. This assessment is partly reasonable when it comes to economic cooperation, which Trump highly prioritises.
China may also persist in institutionalising and strengthening China–Japan–South Korea cooperation, contingent upon improved trust and reconciling historical disagreements and sovereignty disputes. But Japan has repeatedly referred to China’s actions as undermining regional stability, most recently in its Defense White Paper 2024. South Korea has also clarified its alignment with the United States and its allies in Northeast Asia.
If minilateral cooperation is driven by the alignment of shared interests, trilateral cooperation mechanisms in Northeast Asia will be constrained by aspirations between countries which are challenging to reconcile. The US and China’s moves could put Japan and South Korea in a strategic dilemma, where it is difficult to form a China–Japan–South Korea alliance or completely break the US–Japan–South Korea triangle.
Nguyen Thanh Long is a Master’s Student in International Relations at the Ho Chi Minh City University of Social Sciences and Humanities.
Dr Cao Nguyen Khanh Huyen is a lecturer in the International Studies Division, Ho Chi Minh City University of Education.