A tale of two trilaterals with Seoul sitting in the center

Asia’s future will be scripted with the fate of two trilaterals — and South Korea sits at the center of both. The first is the U.S.–Korea–Japan partnership (USKJ), the most explicit security alignment in East Asia. The second is the China–Korea–Japan (CKJ) partnership, a quieter but increasingly consequential alignment built on trade, supply chains, and monetary coordination.

How South Korea positions itself in these two trilaterals has the potential to determine the future of the region.

These two triangles frame the geography of power in Northeast Asia. One rests on hard power and deterrence, the other on markets and monetary systems. One is anchored in Washington, the other in Beijing — and South Korea is the pivot.

Both trilaterals are now central theaters in the larger U.S.–China rivalry. For Washington, the USKJ grouping is the institutionalized expression of its Indo-Pacific strategy — the consolidation of allies under a single deterrence framework aimed at denying China military coercion and technological dominance.

The Camp David summit in 2023 elevated this alignment into a quasi-alliance, complete with missile-tracking integration and joint exercises designed to make any wedge-driving by Beijing politically costly.

For Beijing, the CKJ process — once derided as little more than talk — has matured into a structured mechanism for buffering against U.S. decoupling. The CKJ leaders’ meeting in Seoul in 2024 quietly advanced frameworks for supply-chain resilience, financial coordination, and joint R&D in green tech.

With Trump’s policies impacting both Japan and South Korea, both are increasingly hedging through diversification. These are not headline-grabbing moves, but collectively they point toward an East Asian economic bloc that could, in time, rival U.S.-led initiatives like the Indo-Pacific Economic Framework.

In other words, the trilaterals are not separate tracks. They are parallel contests for the same strategic ground. More worrying, both trilaterals have the potential to stretch beyond their original geometry.

The USKJ trilateral is a temptation to Australia and the Philippines. Canberra’s deep interoperability with U.S. forces and its new security commitments under AUKUS make it a natural adjunct to the USKJ framework. Manila, meanwhile, has re-opened its bases to U.S. forces and is rapidly becoming the southern pillar of deterrence in the first island chain. What began as a trilateral may soon evolve into a broader trilateral-plus format — an Indo-Pacific “NATO” in all but name.

The CKJ trilateral is a temptation to ASEAN. On the economic side, China, Korea, and Japan are already embedded in ASEAN+3, and recent efforts to create joint infrastructure funds and currency-swap mechanisms signal a more coherent regional economic architecture. The CKJ format could act as an executive and influential core to an emerging regional framework, managing the institutions that ASEAN political consensus often leaves paralyzed.

This means Seoul’s choices do not only shape bilateral relations — they shape which trilateral expands faster, and which regional order becomes dominant. This opens avenues to more expansive roles.

First, each trilateral will play a role in the region’s approach towards next-generation technologies — AI, quantum computing, clean energy, and digital finance. The USKJ grouping favors regulatory alignment around trusted supply chains and democratic governance of data. The CKJ bloc, in contrast, emphasizes commercial efficiency and production scale, with China’s industrial capacity offering irresistible pull for Korean and Japanese firms. Korea’s semiconductor sector, caught between export controls and Chinese market demand, is the testing ground for how far economic interdependence can coexist with national security boundaries.

Second, each trilateral will play a role in monetary coordination and currency hedging. The dollar’s dominance gives Washington enormous leverage over Asian finance. Yet the CKJ group has quietly revived discussions about local-currency settlements and regional liquidity safety nets — ideas first proposed during the 1997 financial crisis but blocked by U.S. opposition. If CKJ mechanisms mature, Asia could see the rise of a partial yen-won-yuan clearing system. That would not dethrone the dollar, but it would signal that monetary multipolarity has begun.

Finally, the success or failure of each trilateral will contribute to domestic public acceptance of regional leadership. Each trilateral’s durability depends not only on elites but also on public sentiment. In Japan and Korea, younger generations show ambivalence toward great-power rivalry and skepticism toward U.S. interventionism. In China, nationalism drives the narrative that the CKJ axis is Asia’s natural order. If Seoul’s next administration decides to moderate its enthusiasm for USKJ coordination — emphasizing autonomy over alliance — the balance could shift rapidly, without any formal withdrawal or confrontation.

At the moment, Seoul sits dead bang in the center. Its support for the USKJ grouping tightened under pressure from Biden and under Yoon’s pro-American leadership. It tightened with a clear military focus — missile defense integration, trilateral summits, and intelligence sharing.

Trump loosened this pressure. Tariffs, ICE raids, and investment demands, have justified hedging and made supporting the U.S. more difficult than ever. On top of this, Seoul’s medium-term economic recovery and industrial future is tied to Chinese demand and regional supply chains that will flow through the CKJ framework.

Seoul’s decision does not have to be binary. The notion that it must “choose” between Washington and Beijing oversimplifies the structural realities.

In practice, enthusiasm matters more than membership. A slight reduction in rhetorical zeal, fewer symbolic gestures, or slower implementation of trilateral commitments can send powerful signals without rupturing alliances.

The two trilaterals are not merely alliances or forums — they are architectures of order. Just as the Breton Woods institutions are slowly being transformed or replaced as China grows relative to the U.S, so too will the fate of the two trilaterals be shaped by great power rivalry.

The USKJ structure could anchor a militarized Indo-Pacific, binding Japan and Korea irreversibly to U.S. strategic objectives. The CKJ framework could evolve into an East Asian economic sphere centered on regional production, innovation, and self-financing. If both harden simultaneously, Asia will fracture into competing systems of power and finance.

Asia’s next decade will be defined not by summits or slogans, but by the tempo of these two trilaterals. The United States and China will each continue to press for deeper loyalty from Seoul and Tokyo. But the real test will be how South Korea calibrates its enthusiasm — how it supports both frameworks without surrendering its own agency.