Japan and South Korea Navigate a Turbulent World

The Andong Summit and Its Diplomatic Context

(The Diplomat)

The May 19, 2026, meeting between Japanese Prime Minister Sanae Takaichi and South Korean President Lee Jae Myung in Andong represented more than a routine bilateral encounter. Held in the president's hometown, the summit occurred against the backdrop of rapid shifts in great-power relations following the May 14-15 meeting between U.S. President Donald Trump and Chinese President Xi Jinping. Both Tokyo and Seoul recognized that their shared strategic environment had grown more complex, with the Korean Peninsula emerging as a secondary concern in Washington-Beijing discussions focused primarily on Taiwan, Iran, and trade.

Japanese officials tracked the Trump-Xi exchange with particular intensity because of longstanding tensions over Taiwan. Prime Minister Takaichi received a telephone briefing from President Trump on May 15 while he remained en route from the summit, underscoring the immediacy of Tokyo's interest. President Lee, by contrast, was briefed two days later. This sequencing illustrated differing levels of exposure to the Taiwan contingency and highlighted how each capital calibrates its response to U.S.-China diplomacy.

Aligning on Economic Security Within the Trilateral Framework

Japan and South Korea share a clear assessment that China's economic coercive diplomacy poses risks to both economies. They therefore view deeper cooperation on economic security inside the Japan-U.S.-South Korea framework as essential, with sustained U.S. engagement regarded as indispensable. Concrete steps in this direction have included information exchanges on supply-chain vulnerabilities and coordinated approaches to critical technologies.

Yet the two governments diverge in tone toward Beijing. Seoul seeks to prevent the U.S.-South Korea alliance from becoming entangled in the Taiwan question while preserving workable economic and diplomatic channels with China, partly because of trade dependencies and the persistent North Korean challenge. This difference surfaced in the joint press announcement after the Andong summit: President Lee referenced trilateral cooperation among Japan, China, and South Korea, whereas Prime Minister Takaichi confined her remarks to the Japan-U.S.-South Korea structure. Such nuance helps explain why the Acquisition and Cross-Servicing Agreement between Tokyo and Seoul remains unresolved.

Energy Vulnerabilities and the Strait of Hormuz Question

Both nations confront a common energy predicament. With roughly 90 percent of their oil supplies originating in the Middle East, Japan and South Korea must reconcile alliance obligations with the imperative of avoiding direct confrontation with Tehran. The Andong summit produced tangible progress on this front through an agreement on swap arrangements that would allow each country to cover shortfalls in crude oil and liquefied natural gas.

Washington has requested naval contributions from allies to secure passage through the Strait of Hormuz. Public opinion in both Japan and South Korea remains largely critical of deeper involvement, and both governments have responded with caution. The situation remains fluid. Should the conflict persist or a ceasefire prove fragile, renewed U.S. pressure for burden-sharing would place Tokyo and Seoul in a difficult position. Coordinated responses will be necessary to prevent either capital from facing unilateral penalties. Continuous consultation between the two governments on this dossier therefore carries immediate operational significance.

North Korea's Strategic Calculations and Constitutional Shift

President Trump has expressed interest in another summit with North Korean leader Kim Jong Un, the last such meeting having taken place in 2019. In Seoul, President Lee maintains cautious optimism that improved U.S.-North Korea relations could create space for inter-Korean engagement. Both Tokyo and Seoul nevertheless share concern that any summit bypassing the denuclearization question would establish a troubling precedent.

North Korea, for its part, has intensified ties with Russia, most visibly through the deployment of troops to Ukraine. On May 9, North Korean forces participated for the first time in Russia's annual Victory Day parade. Pyongyang appears confident that support from China and Russia will allow it to weather current pressures, reducing any perceived urgency to accept Washington's invitation. At the same time, North Korea is formalizing its redefinition of relations with South Korea as an "adversarial relationship between two states," removing any constitutional reference to unification. This amounts to a North Korean variant of a two-Koreas policy and is likely to harden the existing division on the peninsula.

Military Modernization and the Search for Regional Public Goods

Many South Koreans express apprehension about Japan's ongoing constitutional revision and military expansion under Prime Minister Takaichi. Yet South Korea itself now ranks fifth globally in conventional military capabilities, roughly comparable to Japan, and has elevated arms exports and force modernization to central elements of national policy. The question therefore arises whether the present moment offers an opportunity for Tokyo and Seoul to articulate a shared understanding that treats their combined capabilities as a stabilizing public good for the region.

Such a framing would require careful domestic political management in both countries. It would also need to be embedded within a broader architecture of reassurance that addresses historical grievances. Without progress on those issues, military cooperation risks remaining limited to technical arrangements rather than evolving into a durable strategic partnership.

Toward a More Resilient Bilateral Architecture

The challenges confronting Japan and South Korea are formidable and interconnected. Economic security, energy vulnerabilities, North Korean nuclear developments, and shifting U.S.-China dynamics all demand sustained attention. Civil society linkages, educational exchanges, and local government cooperation have historically provided ballast during periods of official friction; these channels require continued investment.

Above all, the two governments must institutionalize more frequent and substantive communication. Regular meetings at multiple levels, improved information-sharing protocols, and joint contingency planning would help both capitals anticipate rather than merely react to external shocks. Historical reconciliation remains unfinished business, yet incremental steps on that front can reinforce the practical cooperation already underway. In a turbulent strategic environment, the quality of Japan-South Korea coordination will directly influence stability across Northeast Asia.