What happens in inter-Korean relations does not stay between the two Koreas. Other state actors see their national interests at stake on the Korean Peninsula, motivating broader policy adjustments. While the Republic of Korea (ROK or South Korea) has economically and diplomatically raised its international profile as a “global pivotal state” (MOFA 2022), it could also be said that the Korean Peninsula remains a geopolitical pivot point. Owing to the interdependence and rivalries among geographic neighbors, North Korea’s norm-violating behavior can be a catalyst for change in regional security strategies.

The Kim Jong Un regime’s approach toward Seoul has become increasingly hostile. Since 2022, Pyongyang has launched over 100 ballistic missiles in the process of testing and deploying more capable offensive weapons it claims can deliver tactical nuclear warheads (MOFA n.d.; Van Diepen 2023). In 2024, Kim demonized South Korea as a different country and called for constitutional amendments to define the ROK as the “number one hostile state” and “principal enemy” (Kim 2024). Since May 2024, North Korea has launched thousands of trash-filled balloons to harass South Koreans, and since July, has also blasted loudspeaker broadcasts across the border, affecting residents of Incheon. In September, Kim inspected a uranium enrichment facility and called for an increase in the production of nuclear weapons. Pyongyang has disavowed peaceful unification with Seoul and rejected diplomacy and denuclearization negotiations with the United States, while reinforcing its relationships with Russia and China (Easley 2024).

However, counter to Kim’s intentions, North Korea’s norm-violating behavior is encouraging U.S.-ROK-Japan trilateralism. This is largely due to the Yoon Suk Yeol administration responding to North Korean bellicosity, in part, by prioritizing cooperation with Japan. Rather than press Tokyo for further concessions regarding its incomplete reconciliation over colonial history, South Korea is updating Asia’s security architecture with its partners. Using North Korea as proximate cause for what policymakers also want to do for other reasons is not a new phenomenon (Christensen 1996). North Korea is a serious and urgent threat, but Seoul, Washington, and Tokyo face a broader range of foreign policy challenges for which they are increasing cooperation on cyber and intelligence, economic security, and human rights – with diplomatic implications in and beyond the Indo-Pacific.

I. North Korean Threats Accelerating Intelligence and Cyber Security Cooperation

North Korea’s missile tests and hacking activities have both motivated and justified U.S.-ROK-Japan trilateral cooperation on intelligence and cyber security. In 2022, Pyongyang tested over 85 missiles, of which more than 60 were ballistic missiles, including at least six ICBMs. At a trilateral summit on the sidelines of ASEAN meetings in Phnom Penh in November 2022, President Yoon, President Joe Biden, and Prime Minister Fumio Kishida agreed to share missile warning data in real time. In December 2023, the system was activated just one day after Pyongyang launched its fifth ICBM of the year. Shared data includes a missile’s presumed launch point, flight path, and expected point of impact.

In June 2023, shortly after one of Pyongyang’s attempted military satellite launches fell into the Yellow Sea, the defense ministers of Japan, South Korea, and the United States met in Singapore. The then ROK Defense Minister Lee Jong-sup emphasized that trilateral cooperation is “inevitable” in times of growing North Korean threats (Chae 2023). During the Shangri-La Dialogue, South Korea and Japan also held their first bilateral defense ministerial meeting since November 2019.

The historic Camp David Summit in August 2023 was the first standalone trilateral leaders meeting. It bolstered security and economic cooperation, including closer information sharing (MOFA 2023a). Having expressed concern over Pyongyang and Moscow signing a Comprehensive Strategic Partnership, Seoul, Washington, and Tokyo initiated the Trilateral Security Cooperation Framework (TCSF) under which the three governments plan to institutionalize regular high-level talks, policy consultations, and trilateral defense exercises and exchanges (U.S. Department of Defense 2024).

Japan, South Korea, and the United States are also enhancing coordination on cyber security. In December 2023, the first trilateral working-level talks on North Korea’s cyber threats focused on countering illegal activities – including the stealing and laundering of cryptocurrency – that Pyongyang uses to finance its nuclear and missile programs (Ministry of Foreign Affairs of Japan 2023). Several rounds of trilateral meetings facilitated information sharing to enforce United Nations Security Council (UNSC) resolutions by disrupting malicious IT worker networks and coordinating sanctions on hackers. The three partners are also combating disinformation online, as Washington signed a memorandum with Tokyo and another with Seoul to strengthen cooperation against foreign influence operations (U.S. Department of State 2023, MOFA 2023b).

II. Pyongyang’s Sanctions Violations Encouraging Economic Security Cooperation

Concerns about sanctions enforcement on North Korea, export controls, and possible trade disruptions further encourage Japan, South Korea, and the United States to advance their partnership on economic security. Amid heightened North Korean provocations, the three governments have been working closely with other members of the UNSC. Japan and South Korea are serving two-year terms as non-permanent council members, until 2024 and 2025 respectively (Security Council 2024). Seoul, Washington, and Tokyo are currently pushing for a new mechanism that would effectively replace the UN Panel of Experts, which had monitored North Korean sanctions enforcement since 2009, until its renewal was vetoed by Russia in spring 2024 (Lee 2024).

At the June 2024 Trilateral Commerce and Industry Ministerial Meeting, the three governments jointly expressed concerns about “non-market measures” that could lead to supply chain disruptions (U.S. Department of Commerce 2024). Seoul, Washington, and Tokyo agreed to pursue resilient and reliable supply chains that are transparent, diversified, sustainable, and trustworthy in areas such as critical minerals. Officials also agreed to promote responsible use of emerging technologies such as artificial intelligence (AI) with good governance, while limiting technological exports to countries that might exploit them to the detriment of global security. As part of this effort, the three countries will work with other key actors in the semiconductor industry, including partners in Taiwan.

Trilateral cooperation is also expanding in the pursuit of carbon reduction and energy security. Tokyo and Seoul plan to establish a joint supply network for green hydrogen and ammonia (Yoon 2023). As two of the world’s top three importers of liquefied natural gas (LNG), Japan and South Korea will benefit from sharing LNG data and setting up a supply response system (Lee 2023). The March 2023 ROK-Japan summit resulted in the Korea Gas Corporation (KOGAS) and Japan’s Energy for a New Era (JERA) agreeing to jointly purchase LNG, of which the U.S. is a major exporter. This will allow the two sides to swap and later repay energy resources when one country’s supply runs low. While much economic security cooperation has been ad hoc and reactive to crises, the three governments are now regularizing and institutionalizing such cooperation to get out in front of future challenges and mitigate disruptions.

III. North Korean Human Rights Receiving More Coordinated Attention

Basic freedoms do not exist in North Korea (UNHRC 2014), and during the COVID-19 pandemic, the Kim regime enacted three laws to strictly punish citizens who come in contact with “foreign pollution,” including the death penalty for those who disseminate international content (Easley 2024). Women in detention, including those repatriated from China, are subjected to torture, forced labor, and sexual violence (Kim and Easley 2021). In response, Japan, South Korea, and the United States are increasingly coordinating human rights efforts.

South Korean officials have become more vocal about the issue of Japanese citizens abducted by North Korea, while Japanese diplomats have mentioned the plight of South Korean detainees and unrepatriated POWs in North Korea. Both governments have sponsored United Nations General Assembly Resolutions on North Korean human rights, led discussions in Security Council sessions, and become more outspoken about North Koreans forcibly repatriated to the Kim regime from China. This marks a clear departure from the Moon Jae-in administration, when Seoul often refrained from speaking out about rights abuses and at times abstained from UN General Assembly and Human Rights Council resolutions to avoid offending Pyongyang.

In his August 15, 2024 Liberation Day Speech, Yoon emphasized North Korean human rights instead of talking about Japan’s colonial history (Yoon 2024). He called Japan a partner of a future unified Korea and introduced a new “8.15 Unification Doctrine” advocating for greater access to international information for North Koreans. The speech was controversial, as progressives boycotted the event over Yoon’s personnel decisions and positions on history, North Korea, and Japan. Previous administrations, including conservative presidents Lee Myung-bak and Park Geun-hye, made a point of discussing Japan’s historical responsibility in their Liberation Day speeches (Lee 2012; Park 2013). However, Yoon’s remarks made clear how U.S.-ROK-Japan trilateralism is an answer to the Kim regime’s norm violations.

The overlapping non-permanent Security Council memberships of South Korea and Japan present an opportunity to address human rights. The UNSC has at times failed to hold sessions on North Korean human rights, including a hiatus from 2018 to 2022. However, when serving as the rotating UNSC chair, South Korea was able to encourage and preside over discussion of the Kim regime’s violations and abuses (King 2024).

The trilateral partnership is also expanding cooperation on humanitarian aid to address destabilizing factors such as resource scarcity, corruption, and marginalization of minority groups (USAID 2023). Seoul, Washington, and Tokyo are coordinating support for water security and climate resilience in the Mekong region (White House 2022). The three governments are also coordinating development assistance in Africa. In 2023, the U.S. Agency for International Development and Japan International Cooperation Agency (JICA) agreed to contribute financial and technical support to Ghana’s universal health coverage in partnership with the Korea International Cooperation Agency (KOICA 2023).

IV. Trilateral Cooperation Beyond North Korea

Japan, South Korea, and the United States have common interests by virtue of their shared values, democratic systems, and global trade priorities (Easley 2023). However, there are questions as to whether close trilateral alignment will be sustained. What if North Korea becomes less of a catalyst – by reducing provocations and returning to diplomacy – as Pyongyang seeks to strategically divide Seoul, Washington, and Tokyo? It is unlikely that the Kim regime will come into compliance with international laws and norms anytime soon, so it will be in the three countries’ interests to continue strengthening their cooperation.

Nonetheless, domestic politics and leadership changes can still affect trilateral alignment. With the Liberal Democratic Party’s September 2024 leadership election, Shigeru Ishiba replaces Kishida as prime minister. While foreign policy continuity is expected, Kishida devoted significant attention to the Korean Peninsula compared to Japanese lawmakers who sometimes appear more inward-looking. Meanwhile, prominent opposition politicians in South Korea have a reputation of focusing more on history than future-oriented cooperation, and they may be on the rise as Yoon’s approval rate has declined from 34% in March 2024 to 20% in September 2024 (Gallup Korea 2024). Moreover, a U.S. government that can seem distracted by conflicts in Europe and the Middle East is approaching the November 2024 presidential election. Kamala Harris and Donald Trump could have different policy priorities with contrasting approaches to North Korea, alliance management, and extended deterrence. Despite this, the Camp David process is likely to be maintained by a new trilateral secretariat because such coordination allows the three countries to be more efficient and effective in their foreign and security policies.

North Korea’s nuclear and missile threats may be the immediate drivers of U.S.-ROK-Japan trilateralism, but intelligence and cyber cooperation, economic security initiatives, and human rights efforts have broader applications. China’s size and economic importance call for sophisticated diplomacy. Trilateral cooperation better equips Seoul, Washington, and Tokyo to respond to China’s economic coercion, influence operations, and growing military assertiveness in the Taiwan Strait and East and South China Seas. Just as the Quad and AUKUS are not anti-China coalitions, U.S.-ROK-Japan trilateralism is about upholding international norms and standards. If leaders in Beijing see such trilateral cooperation as against their interests, then they should do more to restrain North Korea and encourage it to return to diplomacy.

Beyond the Korean Peninsula, U.S.-ROK-Japan trilateral cooperation is helping to provide international public goods. From 2022 to 2024, Yoon and Kishida attended three NATO summits together as members of the Indo-Pacific partners (IP4), engaging in defense of the international order by supporting Ukraine against Russia’s illegal invasion (NATO 2024). Economically, Asia was often referred to as the workshop of the world; now the region is a global laboratory. Innovations not only in technology, but also in public policy, can be exported – including on energy and climate, women’s empowerment, and demographics and health (U.S. Embassy in Japan 2023). The Kim regime’s bellicosity and related uncertainties are undoubtedly negative factors for regional stability, but while Seoul, Washington, and Tokyo do more together, trilateral cooperation promises economic and security benefits under a rules-based international order.

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■ Leif-Eric EASLEY (Ph.D. in Government, Harvard University) is a professor at Ewha Womans University in Seoul where he teaches international security and political economics.

■ Sunwoo KIM is a research assistant and international studies undergraduate at Ewha Womans University.

■ Edited by: Jisoo Park, Research Associate
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