Managing Relations with South Korea

Prime Minister Ishiba Shigeru was inaugurated with his new cabinet on October 1. Just a few days later, on October 4, during his inaugural policy speech in the National Diet, Ishiba expressed a strong commitment to advancing relations with South Korea. He stated, “Japan and the ROK acting in close cooperation amidst the current strategic environment is of extreme importance for the interests of both our nations. Although challenges exist between Japan and the ROK, setting my sights on marking the 60th anniversary of the normalization of Japan-ROK relations next year, I intend to take the relationship of trust forged between Prime Minister Kishida and President Yoon as a cornerstone and make Japan-ROK bilateral cooperation even more solid and wide-reaching. Japan, the United States, and the ROK will also work in even closer cooperation.”¹

Shortly after taking office, Ishiba held a phone conversation with President Yoon Suk Yeol, following a call with US President Joe Biden. During his first overseas trip to Vientiane, Laos, Ishiba had a meeting with Yoon on October 10, on the sideline of ASEAN-related summit meetings.² The fact that a Japan-South Korea summit was realized just ten days after Ishiba assumed office was a positive sign for future, bilateral relations.

However, it will not be easy for Ishiba to manage and further develop the Japan-South Korea relationship, solidified since last year. Deeply strained by historical issues over the past 10 years, relations are not just foreign policy matters but also domestic political issues for both countries. To advance the relationship further, Ishiba needs to demonstrate his leadership not only in diplomacy but also in domestic politics. The ruling coalition’s landslide defeat and loss of a majority in the Lower House election on October 27 has made it more difficult to exercise his leadership in Japan-South Korea relations.

The change in the US administration is also likely to impact Japan’s foreign policy toward South Korea. The improvement in Japan-South Korea relations has benefited from the Biden administration’s active support. For instance, the Camp David summit among the US, Japan, and South Korea in August 2023 showcased how the Biden administration has contributed by strengthening trilateral cooperation. How much attention the new US administration, set to take office in January, will give to the US-Japan-South Korea and Japan-South Korea relations will determine the future trajectory of these relationships.

Meanwhile, as Ishiba mentioned in his policy speech, the current severe international situation will continue to serve as a driving force for cooperation between Japan and South Korea. Growing military capabilities and the aggressive posture of China and North Korea in the region, particularly the deepening relationship between Russia and North Korea, spurred by the summit meeting between President Putin and Chairman Kim Jong-un, and the signing of the “Comprehensive Strategic Partnership Treaty” in June 2024, will likely advance the security cooperation between Japan and South Korea further.

This article first briefly reviews the rapid improvement of Japan-South Korea relations since last year and then examines the challenges Ishiba must address in relations, taking into account thinking in both Japan amid political uncertainty and South Korea, divided between conservatives now inclined to back closer Japan ties and doubtful progressives.

Rapid Improvement of Japan-South Korea relations since 2023

The resignation of Kishida marks a turning point in the improving Japan-South Korea relationship, which had been led by Kishida and Yoon. The Kishida cabinet, which began in October 2021, responded positively to measures taken by Yoon, who took office in May 2022. In July 2022, the Yoon administration launched a public-private consultative body to resolve the labor issue during Japan’s colonial rule. After this measure, the first summit meeting between Kishida and Yoon took place in November 2022 in Phnom Penh, Cambodia. In total, they held 13 summits before Kishida’s resignation in September 2024, in 2023 alone, seven summits occurred, reviving “shuttle diplomacy” with leaders visiting each other’s countries. This rapid improvement in Japan-South Korea relations underscores the significant political leadership provided by both Kishida and Yoon.

In early March 2023, the Yoon administration announced a solution for the wartime labor issue involving third-party compensation,³ the biggest challenge for Japan-South Korea relations after the South Korean Supreme Court ruled in favor of the plaintiffs (former wartime laborers) in October 2018, ordering Japanese companies to pay compensation. The Japanese government and companies claimed that this ruling violated the 1965 agreement normalizing diplomatic relations. Nevertheless, the ruling led to the seizure of Japanese companies’ assets in South Korea and could have resulted in liquidating them for compensation. The Yoon administration proposed that the foundation sponsored by South Korean government would provide compensation in place of Japanese companies, a move announced on March 6, 2023.

Following this development, Yoon was invited to Tokyo, the first visit by a South Korean president for a bilateral summit since President Lee Myung-bak traveled to Kyoto nearly 12 years earlier. Subsequently, in May 2023, Kishida visited Seoul earlier than anticipated, reviving shuttle diplomacy and solidifying the improvement in relations. This diplomatic momentum continued with the G7 Summit in Hiroshima in May and the US-Japan-South Korea summit at Camp David in August, leading to the current positive state of strategic diplomacy among Japan, South Korea, and the US.

The trust built between Kishida and Yoon through 13 summit meetings has become an asset for Japan-South Korea relations. Therefore, Ishiba’s first task had to be to firmly sustain this trust between the two sides. With that in mind, on October 2, just a day after taking office, Ishiba held a phone conversation with Yoon, expressing his eagerness to further develop Japan-South Korea relations and his anticipation of working closely with Yoon. During the October 10 summit between Ishiba and Yoon, both leaders agreed to accelerate discussions between their countries to make next year, the 60th anniversary of diplomatic normalization, a year of significant progress in Japan-South Korea relations. They also reaffirmed their commitment to strengthening trilateral cooperation among the US-Japan-South Korea in the field of security.⁴

As Japan and South Korea approach the 60th anniversary of the normalization of diplomatic relations in 2025, it is crucial to establish a “stable and sustainable Japan-South Korea relationship” to avoid the deterioration experienced in the 2010s. In this regard, three key issues that Ishiba needs to address are outlined below.

Expanding Public Support in Japan and South Korea for Improved Relations

The rapid improvement in Japan-South Korea relations since 2023 can be attributed to Yoon’s strong leadership and Kishida’s responsive actions at the political and diplomatic level. In the Japan-South Korea summit held in March 2023, the two leaders agreed to resume the regular consultations and dialogues between the two government that had been halted due to deteriorating relations. In April 2023, the Japan-South Korea security dialogue, which had been suspended for five years, was held,⁵ and in October 2023, the vice-ministerial strategic dialogue, which had been suspended for nine years, also took place.⁶ Almost all governmental consultations and dialogues have been restored in a year. Furthermore, the Japan-South Korea Economic Security Dialogue was established in May 2023.⁷ Japan also lifted its tightened export restrictions on South Korea, implemented since July 2019, and simplified export procedures again. At the same time, the South Korean government fully normalized the operation of the General Security of Military Information Agreement (GSOMIA) between Japan and South Korea.

Despite these rapid political-level improvements, public sentiment in both countries has not fully caught up with the progress, reflecting the current state of Japan-South Korea relations. In particular, many South Koreans are critical of the Yoon administration’s policies toward Japan. For instance, in a public opinion poll conducted by Gallup Korea after the announcement of the third-party compensation measure regarding the wartime labor issue, 59% of respondents opposed the government’s actions due to the lack of an apology and compensation from Japan, compared to 35% who supported it.⁸ Furthermore, with increasing polarization in South Korean politics, the opposition party, which won by a large margin in the April 2024 general elections, continues to criticize the Yoon administration‘s Japan policy. There is strong dissatisfaction in South Korea with the perception that administration has unilaterally made concessions to Japan and demands for Japan’s “sincere response” remain robust.⁹

Against this backdrop, the emergence of Ishiba as prime minister has raised expectations in South Korea that the new Japanese government might adopt a more forward-looking stance on historical issues. This is because he has been viewed in South Korea as a Japanese politician who has shown empathy toward South Korea’s perspective on historical issues. In fact, in his recent book published before the Liberal Democratic Party (LDP) leadership election, Ishiba stated, “without understanding how annexation, which deprived a nation of its culture, language, institutions, and military, damaged the pride and identity of the people of the annexed country, it is impossible to build genuine trust between Japan and South Korea.”¹⁰ Conversely, there was considerable concern about Takaichi Sanae, who narrowly lost in LDP leadership election, because she is a conservative politician close to former Prime Minister Abe and had stated that she would visit the Yasukuni Shrine even if she became prime minister.

Can Ishiba meet South Korea’s expectations? It is not easy. Even if Ishiba personally holds a “liberal” view on historical issues, expressing it as the official stance of his cabinet would require considerable political leadership and effort domestically. Ishiba’s support base within the ruling party is not strong, as evidenced by his narrow victory over Takaichi in the LDP leadership election and his status as a non-mainstream figure within the LDP, where caution toward improving relations with South Korea persisted even after the inauguration of the Yoon administration. Moreover, there is still considerable concern within LDP that a change of government in South Korea in 2027 could lead to a deterioration of relations. In this domestic political environment, for Ishiba to take a stance aligned with South Korea on historical issues, public support is essential. However, Ishiba’s approval ratings are not particularly high. The domestic political situation does not seem to offer ample opportunities to advance Japan-South Korea relations further.

The Yoon administration faces similar domestic political challenges. Yoon’s approval rating has fallen further (to 20% in a Gallup Korea poll in mid-October),¹¹ and the opposition parties hold nearly a two-thirds majority in the National Assembly. Furthermore, the relationship between Yoon and the ruling party’s leader Han Dong-hoon is not favorable. Under these circumstances, even if Yoon continues to push for improved relations with Japan with strong determination, additional efforts will be needed to gain broader public support in further developing Japan-South Korea relations.

In this context, cooperation from the Japanese side is also essential. Even if Ishiba inherits the stance of previous cabinets on historical issues, he should take more proactive leadership on measures that allow both Japanese and South Korean citizens to feel the tangible benefits of improving relations. When Kishida visited South Korea on September 6 for his last summit with Yoon, the two leaders concurred on the importance of ensuring that the fruits of the dramatically improved Japan-South Korea relations are tangibly felt by both countries’ citizens.¹²

During this visit, a memorandum on cooperation in protecting Japanese and Korean nationals in third countries was signed by both diplomatic authorities,¹³ and the two leaders concurred that they would have the two governments consider what specific measures can be taken, including the possibility of facilitating smoother entry procedures of nationals of one country into the other. If Ishiba and Yoon can accelerate these efforts, public support for improving bilateral relations should steadily increase.

Institutionalizing US-Japan-South Korea Cooperation and Advancing Japan-South Korea Relations

In addition to the leadership of Yoon and Kishida, the rapid improvement in Japan-South Korea relations can be attributed to the strong support of the Biden administration and the severe international situation. These factors culminated in the US-Japan-South Korea summit in August 2023. Over the past year, the Camp David agreement has been steadily implemented, particularly in the area of trilateral security cooperation to address the growing military threats posed by North Korea. The three countries have fully activated a real-time North Korean missile warning data sharing mechanism, and conducted trilateral multi-domain military exercises “Freedom Edge.”¹⁴ Additionally, a trilateral working group on North Korea’s cyber threats met three times (December 2023, March 2024, September 2024) based on the Camp David agreement.¹⁵ Strengthening defense and deterrent capabilities against North Korea’s military threats is a central issue of US-Japan-South Korea cooperation, and it is expected that the institutionalization of trilateral cooperation in the military field will continue to progress in the near future.

To further advance US-Japan-South Korea cooperation, three points should be considered. First, it is essential to pursue closer consultation on policies toward North Korea. In Japan, the Ishiba Cabinet has been established, and the US is soon to undergo a change of administration. In South Korea, the Yoon administration announced a new unification policy called the “8. 15 Unification Doctrine” in August 2024.¹⁶ Now is time for the three countries to deepen their understanding of each other’s North Korea policies and refocus efforts on policy coordination among the three countries. Considering this, it would be worthwhile to establish a high-level official consultative body on North Korean issues among foreign and defense authorities of the three countries, and this should address not only deterrence measures against North Korea’s military threat but also diplomacy and negotiation strategies toward North Korea.

During the LDP leadership election, Ishiba expressed his intention to open liaison offices in Tokyo and Pyongyang to serve as a foothold for negotiations with North Korea.¹⁷ If he attempts to engage in dialogue with North Korea without close communication with the US and South Korea, it could jeopardize trilateral coordination, which must be avoided.

Second, it is desirable to further promote trilateral cooperation not only concerning North Korea but also in the context of broader Indo-Pacific strategy. The significance of the current trilateral cooperation, as symbolized by the Camp David agreement, lies in advancing cooperation beyond traditional North Korean issues. Particularly, as policies toward North Korea become centered on deterrence and military cooperation, advancing trilateral cooperation that actively contributes to peace-building in the Indo-Pacific region will significantly expand the horizons of the US-Japan-South Korea cooperation. Trilateral Development and Humanitarian Assistance Policy Dialogue (October 2023)¹⁸ and Trilateral Indo-Pacific Dialogue (January 2024)¹⁹ have already been established, but it will be crucial to see how far the three countries can foster practical cooperation. Given the increasing importance of countries referred to as the “Global South,” such as ASEAN and Pacific Island countries, Japan with long experience in supporting and cooperating with those countries, needs to take the lead in working with South Korea and the US to implement the Indo-Pacific strategies in the region.

Third, a key to solidifying trilateral cooperation is strengthening the relatively weak Japan-South Korea bilateral ties compared to the US-Japan and the US-South Korea alliances. As noted earlier, amid the restoration of communication channels between the Japanese and South Korean governments that had been halted due to deteriorating relations, the exchange and cooperation between defense authorities of Japan and South Korea remained stagnant. The distrust between the two defense authorities that arose from the so-called radar lock-on incident in December 2018²⁰ cannot be easily dispelled, but an agreement was finally reached in June 2024 to resume defense talks and cooperation, and to enhance mutual trust between the two authorities.²¹ A five-year suspension of security cooperation has been a significant loss for both countries, so it is essential to focus on restoring the lost trust as quickly as possible.

As can be seen from his policy speech, Ishiba is positive about Japan-South Korea cooperation and likely to actively engage in bilateral security cooperation due to his expertise in security policy. The Yoon administration has also shown a positive stance, but there is a divide between the conservative and progressive camps regarding security cooperation with Japan, necessitating a cautious approach by the administration.²²

From the Japanese perspective, the time has come to further enhance cooperation with South Korea, which is a very important neighbor, as Japan has been advancing security cooperation with other like-minded countries amid the suspension of Japan-South Korea defense cooperation. For example, Japan has concluded Acquisition and Cross-Servicing Agreements (ACSA) with the US, Australia, the UK, Canada, France, India, and recently German (July 2024).²³ Japan has also signed a Reciprocal Access Agreement (RAA) with the UK, Australia, and the Philippines (July 2024).²⁴ It will be noteworthy whether negotiation on Japan-South Korea ACSA can begin.

With the change of the US administration next year, there is a possibility that the institutionalization of the US-Japan-South Korea cooperation may stagnate or that there might be changes in the nature of the US commitment in the region. Therefore, it is crucial for Japan and South Korea to cooperate to encourage continued constructive engagement from the US. Fortunately, the rapid improvement of Japan-South Korea relations since last year has provided the two countries with an opportunity to collaborate closely in promoting the US’s proactive and constructive role in the region.

Forming a New Partnership of Japan-South Korea Relations in the 60th Anniversary

The Yoon administration aims to issue a joint declaration for the 60th anniversary of Japan-South Korea diplomatic normalization in 2025. Since the start of his administration, Yoon has expressed a desire to upgrade the 1998 Japan-South Korea Joint Declaration (the Obuchi-Kim Dae-jung Declaration). This intent is reflected in South Korea’s National Security Strategy, published in June 2023, which states, “we will build upon the comprehensive vision for the future of both nations outlined in the 1998 Kim Dae-jung-Obuchi Declaration as we confront the past of the bilateral relationship and work toward creating a new future.”²⁵

Indeed, the Japan-South Korea Joint Declaration was a significant document that attempted historical reconciliation between the two countries and affirmed their commitment to jointly addressing issues in the international community. Prime Minister Obuchi “regarded in a spirit of humility the fact of history that Japan caused, during a certain period in the past, tremendous damage and suffering to the people of the Republic of Korea through its colonial rule, and expressed his deep remorse and heartfelt apology for this fact,” and President Kim Dae-jung “accepted with sincerity this statement of Prime Minister Obuchi’s recognition of history and expressed his appreciation for it.” Furthermore, in the declaration, Obuchi and Kim “shared the view that it was extremely important to advance the partnership between the two countries, not only in the bilateral dimension but also for the peace and prosperity of the Asia-Pacific region and the international community as a whole.”²⁶

Despite the desirability of a new joint declaration, it seems that the Japanese side is cautious. This is because firstly, a new declaration would need to include more forward-looking language on historical issues, as requested by the South Korean side. Secondly, there is concern that a change of administration in South Korea in May 2027 could lead to setbacks in Japan-South Korea relations. Thirdly, there is a view that efforts should focus on implementing measures that both countries’ citizens can enjoy directly, rather than creating a new declaration.

Given that Japan-South Korea relations have again become a domestic political issue as well, strong political leadership would be required to issue a new declaration. This has become more challenging following the landslide defeat of the ruling LDP-Komeito coalition in the Lower House election on October 27. At least until the Upper House election in July 2025, there is a lot of uncertainty in Japanese politics, raising questions about how much effort Ishiba will devote to advancing Japan-South Korea relations.

Another issue likely to need careful management in Japan-South Korea relations is the bilateral Continental Shelf Agreement which took effect in 1978. With the agreement due to expire in 2028, Japan and South Korea are expected to hold differing positions on whether it should be renewed. A difficult decision might be required for Japan, which would prefer to end the agreement, to respect South Korea’s wishes to extend it.²⁷

Considering that the Yoon administration, which has led the improvement of relations, has two more years in office and that the international situation is expected to remain challenging, the focus of continuing efforts to advance Japan-Korea relations will be on Japan’s new prime minister, who will, ultimately, be judged for whether he contributes to building a stable and sustainable Japan-South Korea relationship.