By Tongfi Kim
6.6.2025
Introduction
With polls indicating a large advantage for the candidate from the progressive Democratic Party of Korea, few Japanese were surprised by Lee Jae-myung’s victory in the election on 3 June 2025. Based on past experience with South Korea’s progressive camp, many Japanese are pessimistic about the prospect of Japan-South Korea bilateral relations under President Lee. The international environment, however, has changed much from the last progressive South Korean government of Moon Jae-in (2017-2022), during which bilateral relations sank to arguably the worst level since the two countries’ diplomatic normalisation in 1965.
What are the views of Japan regarding Lee Jae-myung?
Japanese government officials reportedly have mixed views on the likely policy of the Lee administration toward Japan. On the one hand, they expect that the new South Korean government’s policy will not be as conciliatory to Japan as that of Yoon Suk-yeol’s government. Yoon was praised or criticised for his exceptionally “pro-Japanese” policy stance on history disputes and security policy. Yoon’s Japan policy was an anomaly even for a conservative South Korean president, and it is unlikely that Lee Jae-myung, whose progressive support base is more critical of Japan on history issues, will take a similarly conciliatory policy toward Japan.
On the other hand, the Japanese government also expects that South Korea’s internal and external circumstances favour a continuation of the Japan-South Korea cooperation that developed under Yoon Suk-yeol. Internally, South Korea’s public opinion has significantly warmed toward Japan in the last few years, and there is much less of a political incentive to adopt an anti-Japanese stance for the sake of domestic political gain. Externally, South Korea faces new security challenges due to the deepening military cooperation between North Korea and Russia, and the uncertainty created by the second Trump administration also increased the value of cooperation between South Korea and Japan.
Although many Japanese have an image of Lee Jae-myung as an anti-Japanese populist leader, Lee in recent months has moderated his stance and emphasised the importance of cooperation with Japan. Back in 2016, Lee wrote on his Facebook page that Japan is still “an adversary state” from a military point of view and he also told a reporter from the Japanese public TV broadcaster NHK that the Korean Peninsula is likely to become the first casualty if Japan continues to pursue militarisation and expansionism. More recently, in 2023, Lee engaged in a hunger strike to protest against the Yoon Suk-yeol administration’s policies, which included its passive stance over Japan’s releasing of treated radioactive water from the Fukushima nuclear plant into the Pacific ocean. Nevertheless, during the electoral campaign and in his inaugural address to the National Assembly on 4 June 2025, Lee emphasised the importance of South Korea-United States (US)-Japan cooperation and Japan-Korea relations under the banner of “pragmatic diplomacy”.
Public opinion shifts as events develop or as political leaders shape certain narratives, but the public opinion in South Korea and Japan is currently conducive to the continuation of cooperation between South Korea and Japan. According to a survey the East Asia Institute conducted in August 2024, South Korean respondents’ favourable perceptions of Japan reached the highest level (at 41.7%) since the survey began in 2013 – although Yoon Suk-yeol’s Japan policy was seen as too conciliatory toward Japan. Japanese perceptions of South Korea has also improved in recent years. For instance, Genron NPO’s survey in August to September 2023 found that 37.4% of Japanese respondents had good impressions of South Korea, surpassing those that had bad impressions (32.8%) for the first time in the history of the survey, which also began in 2013.
What are the key short-term priorities for the South Korea-Japan relationship?
A key priority for President Lee and Japanese Prime Minister Ishiba Shigeru is to meet in person and confirm continuing cooperation between the two governments at the top level. Their predecessors, Yoon Suk-yeol and Kishida Fumio, restarted the so-called “shuttle diplomacy”, where the two countries’ leaders regularly meet. South Korea and Japan are bound to have frictions over time, but the expectation of regular meetings at the top level can limit conflicts to a certain extent. Active collaboration between them may be difficult, but the two governments can at least avoid undermining each other’s core interests. The acrimonious relations between the Moon Jae-in administration and Abe Shinzo’s government is often attributed to history disputes and their ideological differences, but they also considered each other’s North Korea policy to be harmful to their country’s interest. Had they made better efforts to coordinate on their policy toward Pyongyang, they may have had different attitudes toward each other on other issues as well.
Beyond pursuing stable bilateral relations between them, South Korea and Japan need to work together to sustain US-Japan-South Korea trilateral cooperation. Shared values and democracy matter, of course, but South Korea and Japan also have important shared interests such as maintaining the credibility of US alliances, US military presence in East Asia and an open global economic order. The trilateral cooperation reached a historically high level under Joe Biden, Kishida Fumio and Yoon Suk-yeol, but all these leaders have left office by now. The agreements the three leaders signed at Camp David in August 2023 were meant to protect the trilateral cooperation from future shocks, but it is not clear if the momentum of the cooperation can survive changes brought about by leadership changes, especially in the US and South Korea.
In terms of foreign policy signalling, Lee Jae-myung in recent months has been engaging in a balancing act in order to reassure the US and Japan that South Korea under his presidency will not deviate too much in the direction of approaching North Korea and China. Where his actual policy lands is hard to predict because the direction of US foreign policy is difficult to foresee. South Korea and Japan, however, would be better off addressing the uncertainty together than in competition.
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This Korea Chair Explains note is part of a post-election series including notes on the priorities of President-elect Lee Jae-myung, inter-Korean relations and perspectives from the United States and China.
The views expressed in this publication are solely those of the author and do not necessarily reflect the views of the Centre for Security, Diplomacy and Strategy (CSDS) or the Vrije Universiteit Brussel (VUB).
