Editor’s Note: Asia Policy Brief is expanding to include ad hoc, in addition to bi-weekly, analysis of major developments in current events. In today’s special issue, ASPI’s experts assess South Korean President Lee Jae Myung’s visits to Tokyo and Washington, and what the outcomes (and sequence of events) mean for U.S.-Japan-ROK relations. Stay tuned this fall for more rapid responses!
South Korean President Lee Jae Myung visited Tokyo for a summit with Prime Minister Shigeo Ishiba, just days ahead of his highly anticipated meeting with President Trump in Washington. The Lee-Ishiba meeting produced the first joint statement between their two countries in 17 years. The two leaders agreed to rebuild trust and strengthen trilateral cooperation with the U.S. While historical issues remain, both sides are prioritizing stability and flexible dialogue during a period of great uncertainty for international politics and economics. The unprecedented move of visiting Japan before the United States underscored that strong Korea-Japan relations are critical to drive forward U.S.-Japan-ROK trilateral cooperation, a key pillar of the U.S. Indo-Pacific Strategy.
With Ishiba’s advice, Lee’s visit to Tokyo likely facilitated a smoother dialogue with President Trump in Washington. Lee and Trump agreed on the importance of reengagement with North Korea, even while acknowledging that Pyongyang appears disinterested in resuming negotiations on denuclearization. Lee praised Trump’s leadership and role in negotiations with North Korea under his first administration, part of a series of flattering comments of the President. Trump emphasized the importance of alliance cooperation on shipbuilding, a priority for his administration against the backdrop of U.S.-China strategic competition. Despite the more positive atmosphere, the issues of trade and alliance modernization were far from resolved, but—the two leaders agreed to continue these discussions in the future.
Initially centered around prioritizing cooperation on the North Korean nuclear issue, the trilateral has since expanded to include broader cooperation on regional economic prosperity, advanced technologies, and climate change. Today, managing relations with the U.S. has become an important shared priority for Seoul and Tokyo, once seen as the weak link to effective trilateral cooperation. The key question now is how trilateral momentum, as well as ROK-Japan rapprochement, can be sustained under new leaderships in Washington and Seoul, and given political dynamics in Tokyo.
Bleak Outlook for U.S.-Japan-ROK Trilateralism
– By Emma Chanlett-Avery
Trilateralism among the three countries faces an uncertain and daunting path. Both Asian allies are likely to face intense pressure from the Trump administration to increase their own defense spending and the amount they contribute to defray the costs of hosting U.S. troops. Coupled with punishing tariffs, cost-sharing negotiations will further strain Japan and South Korea’s respective relations with the United States, degrading trust and eroding the security guarantees that underpin the alliances. In that context, productive cooperation among the three countries is improbable.
North Korean provocations have driven successful periods of trilateralism in the past. Trilateral exercises have emphasized sharing real-time ballistic missile warnings, coordinating anti-submarine warfare, countering cyber attacks, and enhancing interoperability and communication, all explicitly directed at North Korean aggression. If Trump seeks to restart personal diplomacy with Kim Jong Un as promised during the Lee summit, exercises that seek to deter DPRK provocations may be muted. In addition, both capitals anticipate that their own priorities in dealing with Pyongyang will be ignored if Trump engages directly with Kim. If a Trump-Kim deal involves a moratorium on ICBM testing—the most potent threat to the U.S. homeland—but does not address its other missile and nuclear weapon capabilities, Japan and South Korea’s security will suffer. Coordinating strategies on how to deal with policy outcomes on the Peninsula is a spoke that is ripe for Seoul-Tokyo cooperation.
While Lee sought to underscore the importance of U.S.-Japan-ROK trilateralism, the more remarkable aspect of his summitry is the growing strength of Japan-South Korea bilateral ties. Far from needing the United States to coordinate cooperation between Tokyo and Seoul, Ishiba and Lee are proactively reaching out to each other. Following on the heels of positive statements reflecting on the 80th anniversary of the end of World War II, the leaders have downplayed history-related controversies that have dogged their relationship in the past. The rapprochement is all the more notable given that Lee hails from the progressive political end of the spectrum in South Korean politics, which has traditionally been more critical of Japan’s handling of history issues. Lee’s decision to stop in Tokyo and huddle with Ishiba ahead of his meeting with Trump speaks volumes about the relationship that previously required U.S. facilitation to engage.
Trump’s Tariffs: A Uniting Factor for Tokyo and Seoul
– By Jane Mellsop
The Lee-Ishiba summit provided a valuable opportunity for Japan and Korea to reinforce the importance of their bilateral economic cooperation, especially in light of volatile U.S. trade policy and ensuing global economic uncertainty. The leaders pledged to increase economic cooperation, including in cutting edge sectors of AI and hydrogen. But the meeting was also a chance for the leaders to compare notes on their own dealings with President Trump and the resulting trade deals, which were quite similar in terms of tariff rates, establishing an investment fund, and purchase commitments. While countries have been vigorously pursuing their own economic interests in their dealings with the U.S. to date—and with the trade deals now (largely) done—sharing experiences, lessons learned, and on-going challenges helps both Seoul and Tokyo, not only from a strategic point of view but also with regard to the leaders and their officials forging closer personal relationships.
As the U.S. looks increasingly inward and expands barriers to access its market, Japan and Korea are pursuing their own trade diversification efforts with increased urgency. This includes shoring up their economic relations with each other but also working together in other multilateral fora. Seoul may be more inclined to finally make the move to seek CPTPP membership under this new government and in this current economic environment. It is also worth watching closely how both countries engage with China over the coming months, with increased impetus for Japan-China-ROK FTA negotiations earlier this year, and the Japan-China-ROK trilateral summit expected to be held in Tokyo in October.
Moving on to the Oval Office after Tokyo, President Lee’s trip to Washington did not result in the ROK securing additional trade concessions, with President Trump confirming there would not be changes to the trade deal reached last month. Lee had been hoping to gain preferential treatment for steel and autos in particular, but Seoul’s status as an FTA partner of the U.S. has not resulted in anything more favorable than their direct competitors. The different interpretations with respect to the implementation of the $350 billion investment deal also did not appear to be ironed out by the leaders. The ROK may now find itself in the firing line for Trump’s new moves targeting digital trade barriers, which will add a further area of tension as the details of the July trade deal are worked out over the coming months. There may be another chance for a face-to-face meeting when Korea hosts the APEC summit in October; however, Trump has apparently been non-committal on his attendance.
Adapting to Realities and Identifying Opportunities
– By Rorry Daniels
U.S.-Japan-ROK trilateralism has mostly been defined by the bilateral relationships, with Japan-ROK relations often described as the weak leg of the stool. Recent events challenge the assumption that a common security environment coupled with U.S. support for trilateralism would be the main driver of stronger ROK-Japan relations. On the contrary, it seems the secret ingredient to bridging the gaps between the neighbors was the Trump administration’s indifference toward allies as it pushes through its economic and security priorities. The question on trilateralism moving forward is whether concrete cooperation developed from the change in tone between Lee and Ishiba can hold the stool’s now weaker bilateral legs with the United States
The key to satisfying the U.S. is more focused now on joint commercial opportunities than on military preparedness. While Japan and Korea may find some synergy to rebuild their tech sector connectivity after a suite of export controls stymied development, it’s less clear that the two sides are willing or able to bridge the gaps in their defense strategies. Anxieties about the U.S.’ commitment to extended deterrence, amid the building up of the DPRK and Chinese nuclear arsenals, may prompt both Tokyo and Seoul to develop indigenous nuclear weapons capabilities or push for tactical nuclear deployment. Renewed support for bilateral engagement may help the two sides better communicate their strategic intentions on any potential changes in nuclear policy, but such engagement is still fragile—a major decision that comes as a surprise to the other may damage the progress already made.
President Lee’s visits to both Tokyo and Washington were well-prepared, especially given the short time frame from his inauguration to these early overseas trips. The ROK government was able to project stability and vision after a tumultuous period for the country, but it is still playing catch up on relationship-building with the 2nd Trump administration and other key global actors. Meanwhile, Japan under Prime Minister Ishiba is nowhere near as politically stable or forward-leaning on the rules-based international order as it was under Abe nearly a decade ago. In this regard, Japan and South Korea have a lot to offer each other—a politically secure and ambitious ROK administration can increasingly take on more responsibility in regional and global institutions, while Japan’s industrial strength and key positions in those institutions such as the Quad and CPTPP can advocate for Korea’s greater involvement. Although the Trump administration may not see allies as force multipliers for its agenda, the allies themselves may become force multipliers for each other to soften some of the rough edges of U.S. policy and stabilize the regional economic and security architecture.