Mounting Tensions: A Timeline of Japan-South Korea Relations

October 22, 2019

On October 2, 2019, North Korea tested a submarine-launched ballistic missile, the latest in a series of provocations also designed to test the U.S. alliance network with South Korea and Japan. This incident followed a recent decision by South Korea to cancel a military information sharing agreement with Japan that could also affect trilateral security cooperation with the United States. The apparent unwinding of Japan-South Korea security ties was one of several recent developments that converged to generate a crisis in bilateral relations.

CSIS created a timeline of events documenting decisions each government made over the last year to provide context for issues complicating Japan-South Korea relations. The timeline does not make judgments and is intended as a resource for understanding current dynamics in the bilateral relationship. This online tool also includes reactions from the U.S. government reflecting the strategic implications for all three countries, and hopefully it serves as a springboard for exploring ways Washington can help its allies turn the corner and enhance trilateral coordination in the region.

Q1: What caused the recent deterioration in bilateral ties?

A1: Several issues emerged over the last year to precipitate this latest downturn in bilateral ties. Historical sensitivities—long a source of tension in the relationship—drove the headlines this past year, including decisions by the Supreme Court of South Korea ordering Japanese corporations to pay reparations for forced labor during Japan’s occupation of the Korean Peninsula. Japan argued that these issues were settled back in 1965 per agreements reestablishing bilateral diplomatic relations but South Korea disagreed. Trade friction also featured prominently after Japan imposed export controls on South Korea over the summer and removed it from a list of trusted trading partners. Tokyo insisted the export control decision was based on national security concerns and unrelated to other issues, though Seoul considered it retaliation for the supreme court decisions and subsequently downgraded Japan’s status as a trading partner. Tensions over territorial sovereignty also flared last July after Chinese and Russian military jets reportedly traversed the airspace above islets in the Sea of Japan (East Sea in South Korea) claimed by both countries. And Seoul’s decision to cancel the General Security of Military Information Agreement (GSOMIA) with Japan set to expire this November indicated potential decay in bilateral security ties. The CSIS timeline documents these and other developments animating current tensions between Tokyo and Seoul.

Q2: Has the United States weighed in?

A2: The U.S. government generally encouraged its two allies to resolve their differences via dialogue and emphasized the importance of U.S.-Japan-South Korea cooperation to address the security challenges posed by North Korea and China. The GSOMIA decision invited the most direct response given that a failure to share information in a timely manner would directly impact U.S. national security interests in the context of ballistic missile defense. Washington called for an extension of the agreement and suggested the decision to cancel it put U.S. troops at risk and complicated U.S. efforts to defend the Korean Peninsula. Trilateral coordination among the three governments has continued despite strained Japan-South Korea ties. The State Department recently hosted trilateral consultations on North Korea, and a trilateral defense dialogue could also take shape on the margins of a multilateral security conference in Thailand later this fall. The United States can assume an important role in emphasizing the shared interests of the three countries as a foundation for enhancing trilateral cooperation, a core pillar of U.S. strategy in the region.

Q3: Who benefits from tension in Japan-South Korea relations?

A3: A prolonged deterioration in Japan-South Korea ties could send a bad signal about the vitality of U.S. alliances and potentially embolden North Korea, Russia, and China, which would like to tilt the regional balance of power in its favor by weakening U.S. influence. The July 2019 incident in airspace above the Sea of Japan illustrates how China and Russia could exploit Japan-South Korea tensions. South Korea fired warning shots at Russian military aircraft for crossing into what South Korea considered its sovereign airspace. Japan complained that South Korea did not have a right to do so, which focused attention on discord over territorial sovereignty rather than the security implications of the incident. That was a missed opportunity to spotlight Chinese and Russian coercion in the region and the importance of deterrence in that context. This is one example of how any perceived weakness in Japan-South Korea ties could impact the strategic interests of both countries and those of the United States.

Q4: What’s the way forward?

A4: Historical issues will likely continue to complicate Japan-South Korea ties given political sensitivities in both countries. On the economic front, South Korean and Japanese officials recently discussed the export control issue at the World Trade Organization in Geneva, perhaps a small step towards alleviating trade friction. Continued North Korean provocations could elicit a change of heart in Seoul on the GSOMIA decision, though the prospects for an extension remain uncertain. Despite these challenges, official dialogue between the two governments continues and South Korean prime minister Lee Nak-yon could visit Japan later this week for consultations.

As the CSIS timeline shows, the Japan-South Korea relationship is complex, and near-term solutions to some of these challenges could remain elusive. But the current crisis also presents an opportunity for U.S. leadership to help turn the tide. Encouraging a more positive dynamic between Japan and South Korea is a strategic imperative for the United States, which relies on alliance networking to uphold the regional order.

Nicholas Szechenyi is a senior fellow and deputy director of the Japan Chair at the Center for Strategic and International Studies in Washington, D.C.

Critical Questions are produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).

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