[New Year Special Commentary Series] ④ Managing the Three Major Risks in Japan-ROK Relations in 2025

I. Introduction

Japan-ROK relations generally proceeded smoothly in 2024. Following the South Korean government's proposal of a solution for the wartime forced labor issue in March 2023, the trend of improving relations continued, and particularly through the Camp David Accords, Japan-ROK relations achieved significant progress within the framework of Japan-ROK-US cooperation. The governments of both countries aimed to leverage these achievements to establish a "new era" for Japan-ROK relations in the year marking the 60th anniversary of the normalization of diplomatic relations. However, these expectations have dimmed with the change of leadership in both countries, who were the driving forces behind the improved relations.

Over the past decade, Japan has actively pursued diplomacy centered on safeguarding the rules-based liberal international order under the banner of a "Free and Open Indo-Pacific" to compensate for its declining international influence. Building upon the Japan-US alliance as its cornerstone, Japan has fostered advanced country diplomacy through forums like the G7 and established various regional mini-lateral networks. Last year, the improvement of relations with South Korea, a "missing link," enabled the active engagement in Japan-ROK-US cooperation, Japan-China-ROK cooperation, and Japan-ROK-Australia cooperation. This represents a grand strategy by Japan to maintain the existing order by complementing the declining global leadership of the United States (Son Yeol 2024a).

The issue is the emergence of a second Trump administration. Trump's leadership, which rejects the role of the United States as a provider of public goods for the rules-based international order, seeks to maximize its own material interests through a bilateral, transaction-based approach rather than a multilateral, values-centered one, under the principle of "America First." This fundamentally conflicts with Japan's grand strategy. Notably, Prime Minister Shigeru Ishiba, who replaced Prime Minister Fumio Kishida in October, was forced to abandon his long-held ambitions of establishing a multilateral security system in Asia, akin to NATO, and revising the Japan-US Status of Forces Agreement, due to Trump's potential election. Ishiba's Japan is now in a position where it must prioritize stabilizing Japan-US relations with its diplomatic efforts.

Japan-ROK relations in 2025 are expected to unfold broadly within the context of responding to the security and economic risks posed by a "Trump 2.0" administration. However, the key variables here are the domestic politics of both Japan and South Korea, namely, leadership risks. Depending on the instability of the Ishiba leadership and the potential leadership vacuum in South Korea, bilateral relations will likely experience fluctuations. In particular, the strong influence of domestic political confrontation on ROK policy toward Japan will act as a major variable.

II. Trump Risk

The primary challenge for Japanese diplomacy in 2025 is stabilizing bilateral relations with the Trump administration, set to launch on January 20. Just as previous administrations have established the Japan-US alliance as the "cornerstone of Japan's foreign and security policy," Prime Minister Ishiba also aims to build a stable relationship with President Trump and, based on this, strengthen mini-lateral networks such as Japan-ROK-US, Japan-US-Australia (Quad), and Japan-US-Philippines (Prime Minister's Official Residence, 2024). In this context, the greatest challenges to the Japan-US alliance can be categorized—according to Professor Jaesung Jeon's classification (2025) of Trump's foreign policy—into "primacist" challenges and "restrainer" challenges (Satoshi Mori 2024).

In a "Trump 2.0" scenario, the "restrainers" hold the view that the liberal international order, which the US has upheld, has led to its own decline, and that the pursuit of universal values such as democracy, the rule of law, and human rights is futile. Consequently, they advocate for reduced participation in international organizations for global governance, emphasizing national sovereignty and self-interest, and prioritizing the acquisition of material benefits. This tendency directly conflicts with Japan's position, which centers its foreign strategy on upholding and promoting the rules-based international order. Japan believes that the "Free and Open Indo-Pacific" (FOIP) and its associated rules-based order guarantee its national interests.

If the United States reduces its engagement in international organizations or military interventions abroad, delegates responsibilities for global common challenges to other nations, and narrowly defines its national interests—in other words, if the US scales back its provision of global public goods—does Japan possess the capacity and willingness to fill the void created by the US to uphold the existing order?

More specifically, regarding alliances, the "restrainers" reject the conventional understanding of the Japan-US alliance as a mechanism guaranteeing the legitimacy of US global leadership and a public good that shapes and maintains the rules-based international order. The "restrainer" approach believes the Japan-US alliance is solely a tool for America's peace and prosperity and therefore demands greater mutual responsibility and burden-sharing from Japan. In the economic sphere, they advocate for protectionism and economic nationalism to revive domestic manufacturing, increase well-paying jobs, and create a system of domestic production and consumption. They are prepared to impose tariffs even on allies with whom they run trade surpluses. Trump has already pledged to impose a universal tariff of 60% on Chinese imports and 10-20% on imports from major countries; Japan, as a country with a trade surplus with the US, will find it difficult to avoid these tariffs. Japan will face a double burden: increased costs for hosting US Forces Japan and tariffs on its exports.

Meanwhile, the "primacists" adopt the stance of prioritizing military, economic, and technological capacity building to gain an advantage over China, under the banner of "peace through strength," designating China as the primary threat to the United States. From this perspective, the cooperation of allies such as Japan and South Korea is crucial. In military terms, they seek to counter China by strengthening ties with allies and expanding and deepening integrated deterrence. In economic and technological terms, they pursue an economic security strategy of reorganizing supply chains for key technologies and industries around allies, under the guise of "friend-shoring," and driving an economic decoupling from China. In these two aspects, Japan, as an ally of high strategic value, faces a low risk of abandonment by the US. Conversely, South Korea, as an ally for deterring North Korea, has relatively lower strategic value in containing China and a higher risk of abandonment.

Finally, "Trump risk" could be maximized if the "America First" restrainer approach and the China containment primacist approach intersect and send mutually contradictory messages. For example, if the protectionist and transaction-oriented alliance views of the "restrainer" approach lead to a decline in US global leadership, it could provide China with an opportunity to fill the void, thereby undermining the goals of the "primacists." Furthermore, the Global South might move towards reducing trade with the US, accompanied by criticism of the US, and expanding the BRICS economic sphere. In such cases, America's international prestige would decline, the international economic order would fall into greater chaos, and export-oriented economies like Japan and South Korea would face structural difficulties.

Thus, while "Trump risk" poses a significant challenge to both Japan and South Korea, it also broadens the scope for common interests between the two nations. Both countries share the macro-interest of upholding the liberal international order and support the US's positive role in checking the expansion of China's influence. Both countries view a "Trump 2.0" administration from the perspective of strengthening alliances and share the domestically sensitive issue of increased burden-sharing for US troop presence. They share a critical stance on America's transactional and instrumental view of alliances and, as export-oriented economies with trade surpluses with the US, maintain a position of upholding a free and open economic order against protectionist pressures. Both countries are targets of potential "tariff bombs" from Trump due to their trade surpluses with the US and are in the same boat in seeking to avoid retaliatory tariffs by actively appealing for their significant investments in the US. Lastly, both oppose economic decoupling from China and generally support de-risking from China while maintaining economic interdependence. In essence, in 2025, both Japan and South Korea are identifying incentives for cooperation in various areas.

III. Japan's Leadership Risk

In 2025, Japan faces leadership risks domestically. Prime Minister Ishiba's "New Year's Message" released on January 1 indicates that political stability is his top priority. While identifying diplomatic and security issues, revitalization of the Japanese economy, and public safety and disaster prevention as three major policy tasks, he stated his intention to "seek the broadest possible consensus" based on the coalition between the Liberal Democratic Party (LDP) and Komeito, even mentioning the possibility of a "grand coalition." This suggests the instability of the LDP-led government (Prime Minister's Official Residence, 2025).

Having lost the majority (22 seats) in the House of Representatives election last October, becoming a minority government for the first time in 30 years, the Ishiba administration must seek to expand its coalition with opposition parties such as the Democratic Party for the People and the Ishin no Kai to pass the FY2025 budget. If the budget is rejected or significantly amended due to opposition from the majority parties, the Ishiba administration could face a crisis, and a no-confidence motion could even be passed by agreement among the opposition parties. Even if these risks are overcome in the first half of the year, the Ishiba administration would collapse if it loses the Upper House election in July.

In fact, the "Ishiba risk" stems from more structural problems in Japanese politics. Public distrust is mounting on three fronts: the LDP's dominance, the overwhelming power of the Abe faction within the party, and the LDP government's capacity to govern. When the previous Kishida administration faced a crisis due to a political funding scandal involving factions, the LDP repeated its pattern of holding an election and resolving the crisis by presenting a prime minister with a fresh face from a non-mainstream faction, creating an effect of "pseudo-regime change" that made it feel as if the government had changed (Kim Sung-jo 2024). However, this tactic no longer worked. Consequently, Japan has entered a state of power balance between the ruling and opposition parties, where the government must operate cautiously under the threat of losing power amidst the checks and balances imposed by opposition parties that have significantly expanded their influence (Lee Ju-kyung 2024). Japanese voters, wary of the LDP government's prolonged rule leading to self-serving behavior or a decline in political responsiveness, made a strategic choice to create a power balance between the ruling and opposition parties.

It will be difficult for the Ishiba administration to meet the expectations of the voters. The solution to the political funding scandal, the main issue in the election, ultimately requires structural reform of the LDP. However, as a member of a minority faction within the party, Prime Minister Ishiba prioritizes stability over reform, seeks to maintain the existing factional system, and complies with intra-party sentiment. Furthermore, he lacks the ability and the power base to present an economic policy vision distinct from the Kishida administration (Lee Jeong-hwan 2024). In 2025, Japan's leadership is expected to be influenced by various domestic political variables such as inter-party alliances, coalition structures, and regime changes, making consistent foreign policy implementation challenging.

IV. South Korea's Leadership Risk

Entering 2025, South Korea finds itself in a state of leadership vacuum. In fact, President Yoon Suk-yeol's leadership played a significant role in the improvement of Japan-ROK relations over the past two years. When the Yoon Suk-yeol administration proposed the "third-party compensation plan" as a solution for the wartime forced labor issue in March 2023, Japan-ROK relations entered a phase of thawing, and based on the trust relationship between the leaders, inter-governmental and private exchanges expanded. Subsequently, through the Japan-ROK-US summit and the Camp David Accords, Japan and South Korea, through the mediation of the United States, achieved cooperation and collaboration on expanded issues beyond North Korean nuclear and missile responses, including regional security, economic prosperity and resilience, and the maintenance of a rules-based international order. However, with the departure of Prime Minister Kishida and President Biden, and President Yoon Suk-yeol's suspension of duties due to martial law and impeachment, Japan-ROK government relations are effectively on the verge of suspension.

Behind these political changes lies the polarization of South Korean politics. Over the past decade, South Korean politics has experienced severe political conflict and division due to partisan polarization. The recent imposition of martial law is not only an anachronistic decision by a specific individual but also an extreme manifestation of the conflict and division within South Korean politics. The polarization and extreme confrontation between political forces have led to political paralysis, resulting in martial law and impeachment, and little has changed even during the impeachment process.

The problem is that the polarization of South Korean politics not only divides public opinion and hinders sound policy formulation but also has a significant impact on foreign policy. According to the East Asia Institute (EAI)'s 2024 East Asia Perception Survey (Japan section), supporters of the People Power Party and conservatives evaluated positively on almost all issues, including impressions of Japan, trust, the current government's overall Japan policy, and specific policies, while supporters of the Democratic Party and progressives evaluated negatively (Son Yeol 2024b).

[Figure 1] Impressions of Japan, 2024

[Figure 2] Evaluation of the South Korean Government's Attitude Toward Improving Japan-ROK Relations, 2024.

[Figure 3] Evaluation of the South Korean Government's Response to Sado Mine's UNESCO Listing, 2024.

[Figure 4] Stance on Strengthening Japan-ROK-US Trilateral Military Security Cooperation, 2024.

As shown in [Figure 1], while overall impressions of Japan are improving, supporters of the People Power Party are driving this increase. There is a gap of approximately 30 percentage points between supporters of the People Power Party and the Democratic Party. Meanwhile, the differences in opinions regarding specific policies are even wider. The gap in positive evaluations of the Yoon Suk-yeol administration's attitude toward improving Japan-ROK relations between supporters of the two parties is a significant 48 percentage points, and the gap in negative evaluations is 51 percentage points ([Figure 2]). The difference in positive evaluations of the South Korean government's response to the Sado Mine's UNESCO listing was 28 percentage points, and the difference in negative evaluations was 32 percentage points ([Figure 3]). These partisan differences extend beyond political issues to even security matters. In the case of Japan-ROK-US military security cooperation, which is emerging as the center of the Indo-Pacific architecture through the Camp David Accords, the difference in positive evaluations is 36 percentage points, and the difference in negative evaluations is 29 percentage points ([Figure 4]).

[Figure 5] Trend of Impressions of Japan, 2018-2024.

[Figure 6] Stance on Strengthening Japan-ROK-US Military Security Cooperation, 2018-2024.

As seen in [Figure 5] and [Figure 6], partisan polarization has been on the rise since 2022. The gap in favorability toward Japan between conservatives and progressives, which was around 2-6 percentage points, sharply increased after the regime change in 2022, reaching 12 percentage points in 2023 and 23 percentage points in 2024. Support for strengthening Japan-ROK-US military security cooperation also shows a similar pattern, with the partisan gap, which was almost non-existent until 2022, expanding to 17 percentage points in 2023 and 28 percentage points in 2024. As power shifted from the Moon Jae-in administration to the Yoon Suk-yeol administration, favorability toward Japan and support for Japan-ROK-US security cooperation among progressives sharply declined, while favorability toward Japan and support for Japan-ROK-US security cooperation among conservatives sharply increased. Given that there were no significant events or bilateral relationship changes that clearly distinguished the periods before and after 2022, this difference can only be attributed to partisan support or opposition following the change in government.

The divided public opinion revealed in the opinion polls reflects not the ideologies held by the public but rather the influence of partisan leaders' interests and political manipulation. Issues such as the "third-party compensation plan" and the Fukushima wastewater discharge in 2023, and the Sado Mine's UNESCO listing in 2024, have been framed as divisive issues polarizing the public into pro-Japan and anti-Japan camps and have been exploited for partisan purposes. As a result, Japan policy has become a tool for mobilizing partisan support and attacking opponents. In this context, the space for moderate or bipartisan positions is shrinking. The leadership risk for South Korea in 2025 can be described as the polarization of Japan policy due to political polarization and the politicization of Japan-ROK relations.

V. Conclusion

The challenge for Japan-ROK relations in 2025 lies in managing the three aforementioned risks. The "Trump risk" is creating an incentive for solidarity among US allies. In a shared predicament, there is a need to jointly persuade the US and manage the risks together. For South Korea, Japan policy must, on one hand, prepare for the immediate "Trump risk" by broadening the scope of Japan-ROK cooperation, and on the other hand, in commemoration of the 60th anniversary of diplomatic relations, prepare for the opening of a new era for the next 60 years of Japan-ROK relations from a long-term and strategic perspective. This involves expanding functional cooperation in areas such as security and economy to build a comprehensive strategic partnership, while simultaneously fostering an atmosphere conducive to reconciliation on historical perceptions and creating a virtuous cycle where cooperation on historical issues and functional cooperation proceed in parallel.

To achieve such forward-looking diplomacy, the primary requirement is the reform and improvement of domestic institutions to overcome the polarization of Japan policy. This is intrinsically linked to the issue of resolving political polarization structurally. Despite the presidential impeachment, the political polarization that caused this extreme politics has not changed at all. Only when reforms are made to new systems that allow for the reflection of the majority voice and political consensus, moving away from the current political system that leads to extreme political confrontation and paralysis, can bipartisan foreign policy and grand strategy emerge. ■

References

Kim Sung-jo. 2024. "[2024 Japan Election Issue Briefing] ② Crisis of LDP Politics: Long-term Rule, Political Funds, and Political Reform." EAI Issue Briefing. October 31.https://eai.or.kr/new/ko/pub/view.asp?intSeq=22672&board=kor_issuebriefing(Accessed: January 7, 2025.)

Son Yeol. 2024a. "[New Year Special Commentary Series] ⑦ Japan-ROK Relations in 2024 Practicing the Spirit of Camp David: Challenges and Prospects." EAI Commentary. January 11.https://eai.or.kr/new/ko/pub/view.asp?intSeq=22299&board=kor_issuebriefing(Accessed: January 7, 2025.)

______. 2024b. "[EAI Issue Briefing] Japan-ROK Relations Swayed by Political Polarization: Relationship Improvement and Public Opinion Division Revealed in 2024 Opinion Poll." EAI Issue Briefing. September 19.https://eai.or.kr/new/ko/pub/view.asp?intSeq=22667&board=kor_issuebriefing(Accessed: January 7, 2025.)

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Prime Minister's Official Residence. 2024. "Policy Speech by Prime Minister Shigeru Ishiba at the 214th Session of the Diet."https://www.kantei.go.jp/jp/102/actions/202410/04shu_san_honkaigi.html(Accessed: January 7, 2025.)

Prime Minister's Official Residence. 2025. "Prime Minister Shigeru Ishiba's New Year's Message for Reiwa 7."https://www.kantei.go.jp/jp/103/statement/2025/0101nentou.html (Accessed: January 7, 2025.)

Satoshi Mori. 2024. “Foreign Policy and Defense of the Second Trump Administration (1)—Security Views of Isolationists and Prioritarians and Implications for Allies—.” The Sasakawa Peace Foundation Policy Brief No. 173 | November 25, 2024. https://www.spf.org/jpus-insights/spf-america-monitor/spf-america-monitor-document-detail_173.html (Accessed: January 7, 2025.)

■ Yeol Son_Director of the East Asia Institute, Professor at the Graduate School of International Studies, Yonsei University.

■ Contact and Editing: Hansu Park_Research Fellow at EAI

    Inquiries: 02 2277 1683 (ext. 204) hspark@eai.or.kr