Japan, explained.
The special aircraft of South Korean President Lee Jae-myung departing Haneda Airport, Tokyo (David Mareuil/Anadolu via Getty Images)
Lee and Ishiba’s summit signals a shift from historical grievances to practical cooperation, but politics could derail progress.
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Pragmatism reigns as Japan and South Korea look toward the futurePragmatism reigns as Japan and South Korea look toward the future
South Korea’s new President Lee Jae Myung visited Tokyo last week for a bilateral summit hosted by Japan’s Prime Minister Ishiba Shigeru. The timing was packed with symbolism: it was Lee’s first official state visit, just ahead of a trip to Washington, and only a few days after the 80th anniversary of the end of the Second World War in Asia. The fact that Lee, once an outspoken critic of Japan over its wartime past, chose the country for his first diplomatic mission reflects a personal shift to a more pragmatic brand of politics and the broader geopolitical changes in the region.
In Ishiba, Lee found a willing diplomatic partner. A self-styled “defence geek”, Ishiba has a regionalist bent and seeks to rebalance East Asian security. While his most famous past proposal, the establishment of an Asian NATO-like security alliance, is unrealistic at present, closer South Korea ties align with his worldview and strategic objectives. Deeper cooperation could strengthen both countries’ relative standing in the face of a stronger China and increasingly unreliable ally in the United States.
Lee and Ishiba were notably affable during the summit, Lee describing the two leaders as “close friends”. The summit produced the first joint declaration between the countries in 17 years, and the first involving a politician from South Korea’s political left since the Kim–Obuchi Joint Declaration in 1998.
Issues related to Japan’s colonial past were mostly left untouched. Rather, the focus was on the future, such as cooperation in technology development for areas including hydrogen and AI. The summit was noteworthy for the commitment to strengthen economic cooperation with US tariffs looming in the background. Stressing that both countries faced similar demographic challenges, the leaders agreed to step up lower-level consultations on policy responses.
South Korean President Lee Jae Myung, left, at a press conference with Japanese Prime Minister Shigeru Ishiba following talks in Tokyo on 23 August 2025 (Kyodo News via Getty Images)
Buoyed by shared competencies in their manufacturing sectors, the Japan-South Korea economic and trade relationship is already quite expansive. Japan is South Korea’s fourth largest trading partner. However, there is clear potential for expanded ties, an aim which has been hampered in the past by overlapping areas of competition, such as in the auto sector, and diplomatic spats.
A clear trend towards greater private-sector cooperation can help overcome these impediments, with numerous joint ventures between Japanese and South Korean companies popping up – perhaps most notably including one between major auto-makers Hyundai and Toyota. This has put the 2019 trade dispute, which escalated after South Korean court rulings on the sensitive “comfort women” issue, firmly in the rearview mirror.
Nevertheless, more work is needed to insulate the countries’ economic relationship from potential political pressure.
As ever, the biggest risk for the countries’ relationship is domestic politics.
On security, the summit ticked all the expected boxes. This included restating a shared commitment to denuclearise the Korean peninsula – an aim that looks increasingly beyond reach. Nothing much was said about China and the United States in the public declaration, though it seems sure that the relationships would have been discussed between the two leaders. While South Korean officials argued that the summit was “meaningful in that it strengthened Korea-US-Japan trilateral cooperation”, the three-country security cooperation set up during the Biden era still faces many challenges. While lower-level meetings have survived leadership changes in all three countries, Trump’s personal commitment to the idea remains unclear.
Perhaps the most notable development was that the official press release from the summit failed to mention the “Free and Open Indo-Pacific”, an umbrella term long-used by Japan and its partners to implicitly signify deterrence against China. This could be signalling a more pragmatic approach towards Beijing as well – both leaders are considered to be more doveish on China than their predecessors.
Overall, the Ishiba-Lee summit was an important step for two countries who increasingly rely on each other, but its lasting significance will depend on what comes next. Concrete steps to formalise and institutionalise the commitments made will determine whether the Japan-South Korea rapprochement is sustainable.
As ever, the biggest risk for the countries’ relationship is domestic politics. While Ishiba has proven himself remarkably resilient despite two straight election setbacks, he is still facing a challenge by the conservative wing of his Liberal Democratic Party, which is more hawkish on South Korea. In contrast, Lee appears to be in a much more stable position, maintaining high approval ratings. Still, there is always the possibility that he returns to critiquing Japan on historical issues if he faces domestic pressure and feels the need to shore up his base.
With that in mind, both leaders should leverage the moment to build mechanisms that outlast them, ensuring that Japan and South Korea can finally move beyond the past.
About the author
Maximilien Xavier Rehm
Maximilien Xavier Rehm is a postdoctoral researcher at the Graduate School of Global Studies, Doshisha University, Kyoto.
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