Abstract. This article examines the revival and strengthening of the Japan-US-South Korea geopolitical triangle, as well as its international role in the Asia-Pacific region. This military-political alliance was formed by the US during its confrontation with the USSR in the Asia-Pacific region during the first Cold War. But at that time the trilateral alliance was not fully fledged, since Japan and South Korea were locked into bilateral security treaties with the US and did not engage in direct military cooperation with each other. After the end of the Cold War and the collapse of the Soviet Union, this geopolitical construct became irrelevant. The aggravated problems of Japan’s colonial rule on the Korean peninsula in the first half of the 20th century kept political relations between Japan and South Korea in a state of tension until very recently.

Now, during Cold War 2.0, Washington, with the support of Tokyo and Seoul, is seeking to revive and use this triangle as part of its Indo-Pacific strategy, but this time to contain China’s growing economic and military might, as well as eliminate the so-called nuclear missile threat from North Korea. An important role in the institutionalization of the trilateral alliance was a summit of the US, Japan, and South Korea, held on August 18, 2023, at the US presidential retreat Camp David.

The role of the triangle in Washington’s Indo-Pacific strategy increased due to the rise to power in South Korea of Yoon Suk Yeol, who took a conciliatory position toward Japan, and Japan’s policy of ramping up its military power and creating an offensive potential. The revival of the Japan-US-South Korea triangle at Camp David helped energize talks on creating a parallel triangle in Northeast Asia consisting of China, Japan, and South Korea with the aim of establishing economic and political cooperation between the three countries. At the same time, it is possible that the continued instability of the Tokyo-Seoul axis may once again become the Achilles’ heel of the Japan-US-South Korea triangle.

A military-political alliance in the form of a Japan-US-South Korea triangle was created by the US during its confrontation with the USSR in the Asia-Pacific region during the Cold War. At that time, however, this triangle was largely informal, as Japan and South Korea – both of which had bilateral security treaties with the US – primarily played supporting political and logistical roles in Washington’s confrontation with the USSR in the region. There was virtually no direct military cooperation between Tokyo and Seoul, although there was also no open antagonism between them, given the need for unity among the US and its Asian allies in the face of the “Soviet military threat.” During this period, US forces stationed in Japan and South Korea played a central role in Washington’s military strategy aimed at “containing communism” in Asia.

After the end of the Cold War and the collapse of the Soviet Union, this geopolitical triangle, which had operated under US auspices, lost much of its relevance. Moreover, it became clear that the “Japan-South Korea” side of this triangle was drawn in dashed lines. When the anti-Soviet bonds of the triangle dissolved, historical issues – especially those linked to Japan’s colonial rule over the Korean Peninsula in the first half of the 20th century – resurfaced.

These painful historical issues have kept political relations between Japan and South Korea tense for the past quarter-century, despite the two countries becoming significant trade and economic partners. During this period, Tokyo and Seoul’s security cooperation was largely mediated and pressured by Washington. Now, in the context of “Cold War 2.0,” Washington aims to revive and leverage this triangular alliance as part of its Indo-Pacific strategy, primarily to contain China’s growing economic and military might. A key step in that initiative was the US-proposed summit of Japan, South Korea, and the US, held on August 18, 2023, at Camp David, the American presidential retreat. However, the durability of this geopolitical construct remains in question.

The Camp David trilateral summit and its implications for the security framework in the Asia-Pacific region have already been addressed by both Russian and international experts and researchers. These analyses explore the motivations behind the revival of the Japan-US-South Korea alliance, as well as its trends, challenges, and prospects.1 This article represents the author’s attempt to offer a personal perspective on this alliance.

A Historic Summit?

The Japan-US-South Korea summit at Camp David marked the culmination of years of US efforts to reconcile and bring closer its Japanese and South Korean allies. President Joe Biden has supported that process since his tenure as vice president in the Barack Obama administration. The leaders of Japan and South Korea were the first foreign dignitaries received by Joe Biden in Washington following his presidential inauguration. Japan and South Korea were also the first countries Biden visited in Asia. Their importance was further underscored by the fact that their leaders were the first to be invited to Camp David during Biden’s presidency.

The summit, the first standalone meeting (not held on the sidelines of an international forum) involving President Joe Biden, Japanese Prime Minister Fumio Kishida, and South Korean President Yoon Suk Yeol, symbolized the significance of trilateral cooperation, since Japan and South Korea are key US allies in the Asia-Pacific region. The summit followed a rapprochement and the resumption of high-level shuttle diplomacy between Japan and South Korea in 2023, after 12 years of virtual stagnation in their relations. That same year saw seven summit meetings between Fumio Kishida and Yoon Suk Yeol.

Two documents were adopted at the summit – the Camp David Principles and the Spirit of Camp David: Joint Statement by Japan, the Republic of Korea, and the US. These documents outlined the framework for future cooperation, including regular trilateral meetings at various levels involving heads of state, foreign ministers, trade ministers, and defense officials. The summit also resulted in a decision to hold annual joint military exercises involving Japan’s Self-Defense Forces, the US Armed Forces, and South Korea’s military. To strengthen economic security, the three countries committed to close cooperation, launching “early warning system pilots” to facilitate rapid information sharing and prevent disruptions in global supply chains. Beyond security and economics, the scope of cooperation will include the exchange of advanced technologies, joint development projects, health care, people-to-people exchanges, and more.2

The trilateral summit was part of the broader, multi-level strategy of a Free and Open Indo-Pacific (FOIP), initially articulated by former Japanese Prime Minister Shinzo Abe and adopted in 2017 by then US President Donald Trump. This strategy emphasizes the creation of a network of formal and informal multilateral mini-alliances in the region, such as the Quad (comprising the US, Japan, Australia, and India), AUKUS (a trilateral Anglo-Saxon alliance of Australia, the UK, and the US), and Five Eyes (an intelligence-sharing alliance among the US, the UK, Canada, Australia, and New Zealand), among others. All these groupings, to varying degrees, serve the overarching goal of containing a “rising China,” which is perceived not only as a challenge but as a threat to the countries involved in these alliances. Now, the US-Japan-South Korea triangle has joined this lineup, taking a significant step at Camp David toward becoming a full-fledged military-political alliance.3

This transformation has been greatly facilitated by changes in South Korea’s approach to security. Until recently, Seoul’s military strategy had been traditionally focused on the Korean Peninsula. However, the administration of Yoon Suk Yeol, who came to power in 2022, has adopted a broader regional perspective. Under Yoon’s presidency, South Korea has undergone a sharp geopolitical pivot. His administration decisively abandoned the dialogue-oriented and engagement-focused approach to North Korea, which was a hallmark of his predecessor Moon Jae-in’s foreign policy, and has reinforced a confrontational stance toward Pyongyang.

This significant geopolitical shift also led the South Korean government to seek rapprochement with neighboring Japan. Seoul deprioritized contentious historical issues in favor of normalizing relations with Tokyo and fostering a growing trilateral partnership with Japan and the US in regional and global affairs. In December 2022, the Yoon administration unveiled its Indo-Pacific strategy, which redefined South Korea’s role as a state with both regional and global approaches to its security. The document called for enhanced maritime security cooperation in the region, specifically mentioning the South China Sea and the Taiwan Strait. However, Seoul attempted to maintain a nonconfrontational stance toward China in its strategy, identifying it as a key partner while emphasizing the importance of trilateral cooperation among Seoul, Tokyo, and Beijing.4

Japan, for its part, has for nearly two decades been building partnerships with India and other countries in South and Southeast Asia, advocating for stronger economic and security ties across the Indo-Pacific region. A significant driver of this policy has been the containment of China’s growing economic and military power within the framework of the FOIP strategy. Tokyo’s accelerated military buildup and the development of offensive capabilities – including the capacity for missile strikes on enemy bases – have further bolstered the US-Japan-South Korea triangle’s role in Washington’s regional strategy. This shift, which challenges Japan’s pacifist Constitution, was formalized in the updated National Security Strategy, adopted in December 2022, and other defense-related documents. These documents, using various nuanced phrasing, identify China, North Korea, and Russia as the primary sources of military-political tension in the Asia-Pacific region and the main security challenges facing Japan.

At the Camp David summit, China effectively became the focal point of united efforts by the US, Japan, and South Korea to contain Beijing in the areas of economics, politics, and security. North Korea’s missile and nuclear program also serves as a unifying factor for the three countries’ military-political and economic actions aimed at neutralizing the “North Korean threat” to their security. Unsurprisingly, the leaders of the three countries at Camp David devoted significant attention to the region’s most pressing hotspots, including the Korean Peninsula and Taiwan. The summit participants also jointly condemned Russia’s “aggression” against Ukraine.

The visit to Pyongyang by Russian Defense Minister Sergei Shoigu and Li Hongzhong, a member of the Politburo of the Central Committee of the Communist Party of China and First Vice Chairman of the Standing Committee of the National People’s Congress, in late July 2023 to attend the parade marking the 70th anniversary of the end of the Korean War added another dimension to the evolving trilateral cooperation among Seoul, Tokyo, and Washington. This visit, set against the backdrop of Russia’s ongoing Special Military Operation (SMO) in Ukraine and the potential for trilateral collaboration among Beijing, Moscow, and Pyongyang, served as a catalyst for closer alignment between the US, Japan, and South Korea.5

At Camp David, the leaders of Japan and the US also held a bilateral meeting to discuss further steps to strengthen their military alliance. Under the pretext of addressing the development of hypersonic weapons by Russia, China, and North Korea, Kishida and Biden agreed to jointly develop a new missile capable of intercepting such weapons. They also reaffirmed close cooperation in countering China’s “hegemonic actions.” Regarding Russia’s SMO in Ukraine, Kishida and Biden pledged that Japan and the US, alongside other G7 nations, would continue imposing sanctions on Moscow and providing support to Kiev.

The timing of the Camp David trilateral summit was strategically chosen to advance closer military-political cooperation among Japan, the US, and South Korea before elections in all three countries in 2024 that could complicate the domestic standing of their leaders or result in leadership changes. Of the three, Yoon Suk Yeol faces the most challenging political environment. Elected by a narrow margin, the South Korean president is contending with an opposition-dominated parliament, where anti-Japanese sentiment runs high. The opposition retained its significant majority in the parliamentary elections held on April 10, 2024, meaning Yoon will face a hostile legislature until the end of his term in 2027. Reflecting these concerns, Japan’s Ministry of Foreign Affairs highlighted in its 2024 Diplomatic Bluebook that the defeat of Yoon’s ruling party in South Korea’s recent general elections could strengthen leftist forces critical of Japan. The Japanese government has been advised to closely monitor South Korea’s political developments.6

Fumio Kishida, too, faces the risk of losing his position as leader of Japan’s ruling Liberal Democratic Party and, consequently, his premiership in September due to economic challenges and political scandals among the ruling elite. Meanwhile, Biden is expected to run for re-election in November with uncertain prospects. For all three leaders, therefore, it was critical to institutionalize trilateral cooperation as early as possible.7 Moreover, Biden needed to showcase the growing unity among the three countries ahead of his planned meeting with Chinese President Xi Jinping in November 2023 on the sidelines of the APEC summit in San Francisco. According to Japanese experts, the Camp David summit was intended to send a clear signal to China, which continues to expand its military power and engage in “coercive behavior” on the global stage.8

The agreements reached at Camp David paved the way for military cooperation among Japan, the US, and South Korea, which was difficult to envision just a short time ago. In October 2023, their defense ministries finalized the establishment of a trilateral hotline, designed for use by leaders (or their top national security advisers) during security crises. That same month, the three countries conducted their first-ever joint air force exercises, which international experts view as part of Washington’s “extended deterrence” strategy, encompassing the potential use of nuclear weapons. During these drills, South Korean and Japanese fighter jets escorted a US B-52 bomber capable of carrying nuclear weapons over the Sea of Japan for the first time in history.

In December 2023, Japan, South Korea, and the US developed multiyear plans for joint exercises, and in January 2024, they held their first-ever trilateral naval drills in open waters south of South Korea’s Jeju Island. The exercises included the US Navy’s nuclear-powered aircraft carrier Carl Vinson and focused on capabilities to respond to nuclear and missile “threats” from North Korea and block the maritime transportation of weapons of mass destruction.9 Notably, the experience gained during such exercises could potentially be used against China and Russia if necessary. However, some Western experts caution that the normalization of Japan-South Korea defense relations still has a long way to go. While the joint air force exercises have been hailed as a signal of a “new era” in security relations, questions remain about whether they represent a genuine shift or merely another oscillation in the pendulum of trilateral defense cooperation.10

Weaknesses

At the Camp David summit, the leaders of the US, Japan, and South Korea made significant progress toward institutionalizing their military-political triangle. As noted, in recent years, this triangular relationship has become a crucial element in the US-led network of regional structures designed to contain China in the Asia-Pacific region. However, the strength of the Japan-South Korea side of the triangle remains in question, as unresolved issues stemming from Japan’s colonial past on the Korean Peninsula persist. These issues have largely been “swept under the rug” through deliberate pressure from Washington, which is keen to enhance the effectiveness of this geopolitical construct.

Unresolved historical issues in Japan-South Korea relations include the “comfort women” issue (young Korean women forced into sexual slavery for the Imperial Japanese Army during the Pacific War), the territorial dispute over the Seoul-controlled Liancourt Rocks, demands for Japanese companies to compensate Koreans forced into labor in Japan, and South Korea’s push to rename the Sea of Japan as the East Sea, among others.11 Nevertheless, Yoon Suk Yeol, who assumed the South Korean presidency in 2022, surprised many observers by prioritizing improved relations with Japan and relegating unresolved issues to the background. As Haeyon Kim, senior program officer at the Asia Society Policy Institute in Washington, notes, President Yoon created a stir by unprecedentedly referring to Japan as a “partner” during his August 15, 2023, speech marking the anniversary of Korea’s liberation from Japanese colonial rule in 1945. This speech served as an ideal prelude to the first standalone trilateral summit of US, South Korean, and Japanese leaders just days later.12

However, by early 2024, these “swept under the rug” issues resurfaced. In April, South Korea’s Ministry of Foreign Affairs officially expressed disappointment and regret over a ritual offering made on behalf of Japanese Prime Minister Fumio Kishida (albeit in a personal capacity) to the Yasukuni Shrine, seen in South Korea as a symbol of Japanese militarism. This was compounded by visits to the shrine by members of the Japanese cabinet. Meanwhile, the Japanese government lodged a protest after South Korean opposition lawmakers from the Democratic Party visited the disputed Liancourt Rocks in the same month. This visit was not only seen as a provocation toward Japan but also as a challenge to the perceived pro-Japanese stance of President Yoon Suk Yeol.

A potentially more significant test for the nascent Tokyo-Seoul partnership, according to Kim, may come from Japan’s decision to release 1.3 million [metric] tons of treated radioactive water from the damaged Fukushima Daiichi Nuclear Power Plant into the Pacific Ocean. Although the International Atomic Energy Agency (IAEA) approved the release, it sparked outrage among the South Korean public and has the potential to rekindle tensions between the two nations. This issue, while a major concern for leaders, was not included in the official agenda of the Camp David summit. Many in Seoul believe that Yoon has made excessive concessions to Japan, which have unnecessarily strained relations with China and North Korea.13 Yoon’s approval rating in South Korea plummeted from over 50% in mid-2022 to 29% by early February 2024.14

The persistent fragility of relations between the two key Asian allies of the US is not solely due to the historical memory of the South Korean public. It is also rooted in the explicitly military focus of the Washington-Tokyo-Seoul triangle on containing China and North Korea. According to former South Korean foreign minister Yoon Young-kwan, the Camp David agreement to deepen military cooperation has taken the geopolitics of Northeast Asia into uncharted territory. In his view, deterrence alone is insufficient in Northeast Asia. China and North Korea are likely to counter efforts to institutionalize cooperation among the US, South Korea, and Japan. To fully realize its potential, this new framework of deterrence must be accompanied by openness to dialogue with both China and North Korea.15

According to a South Korean analyst, the biggest threat to the revived Japan-US-South Korea triangle lies in the potential return of Donald Trump to the US presidency in November 2024. During his previous tenure, Trump significantly downplayed the importance of Japan and South Korea in US foreign policy in the Asia-Pacific region, raising serious doubts in both countries about whether the US would honor its alliance commitments in a crisis.16 By early 2024, US allies in East Asia were already expressing concerns about how the outcome of the November election might affect Washington’s regional policies.17

To hedge against foreign policy and economic risks in the event of Trump’s return, Tokyo dispatched former Japanese prime minister Taro Aso, a political heavyweight, to meet Trump in the US in April 2024. During their meeting in New York, the two discussed bilateral economic and security relations. Aware of the delicacy of this situation – particularly given Biden’s warm reception of Prime Minister Kishida during the Camp David summit and Kishida’s subsequent state visit to Washington on April 10, 2024, where the two leaders declared a “new era” in the US-Japan alliance – the Japanese government sought to downplay the significance of Aso’s meeting with Trump. Tokyo stated that Aso had met Trump merely as a lawmaker, not as an official government representative.18

Some Japanese experts also view the formation of a Japan-US-South Korea military-political alliance with caution. In an editorial, the newspaper Hokkaido Shimbun warned that such a move could entangle Japan in US military strategies directed against China. According to the newspaper, Japan and South Korea have been placed on the front lines of Washington’s “containment network” against China. The publication argued that Japan should avoid blindly following the US and instead pursue more independent decisions in its diplomacy.19

Parallel Triangles

The revival of the Japan-US-South Korea triangle at Camp David has also spurred efforts to reinvigorate another, purely Asian triangle: Japan-China-South Korea. Trilateral summits among these countries had not been held since 2019. The leaders of the three major East Asian nations first met expressly for trilateral talks, separate from international conferences, in 2008. Subsequent annual meetings facilitated cooperation on various issues, including responses to the financial crisis, climate change, and disaster prevention. The summits also explored the possibility of creating a Northeast Asian free trade zone. However, negotiations were suspended for nearly four years due to the COVID-19 pandemic, compounded by significant deterioration in Japan-China and Japan-South Korea bilateral relations.

Shortly after the Camp David summit, representatives of the three countries’ foreign ministries met in Seoul in late September 2023 and agreed to resume high-level trilateral meetings as soon as possible. There was even hope of holding a summit by the end of the year. However, shifts in global and regional power dynamics, heightened security tensions, and escalating trade and economic disputes between China and the US altered the countries’ motivations and willingness to cooperate within the Northeast Asian triangle.

South Korea initiated the effort to revive trilateral Japan-China-South Korea summits, with Japan supporting this initiative in the context of improving bilateral relations. Chinese President Xi Jinping also expressed a positive stance toward holding another summit. According to Japanese experts, as China’s economy slows, Beijing hopes to strengthen relations with Japan and South Korea to revitalize its semiconductor industry and attract investments. These experts further suggest that China aims to leverage the regional triangle not only to monitor Japan and South Korea, which are deepening security cooperation with the US, but also to drive a wedge between Washington and its Asian allies. For their part, Tokyo and Seoul seek to engage with Beijing through the triangle to distance China from its military cooperation with Moscow, which deeply concerns both nations. Additionally, Japan and South Korea hope to involve China in containing North Korea, whose advancing missile and nuclear capabilities they regard as the greatest threat to their national security. Lastly, both countries view the trilateral summits with China as an additional platform for their leaders to address pressing bilateral issues.

However, significant shifts in the balance of economic influence and military power between China on one side and Japan and South Korea on the other have led to a new paradigm of interaction within this regional triangle. Japanese expert Ryosuke Hanada argues that in the past, Japan and South Korea engaged with China from a position of economic superiority – an advantage they no longer possess. Now, the dynamic has shifted to a “two-against-one” logic, with two smaller nations negotiating with a giant. Moreover, China perceives the influence of the US behind Japan and South Korea and must think about how to draw them away from Washington. This dynamic has been bolstered by recent improvements in Japan-South Korea relations. Hanada writes: 

“The newfound Kishida-Yoon partnership will allow the two countries to jointly engage with China. This time, however, is not for bringing China into the global economy or changing China’s domestic rules and systems. Both countries should stabilize their own bilateral relations with China by anchoring them to the trilateral mechanism to preserve their leverage against China in their respective bilateral negotiations. Realizing this objective requires Japan and South Korea not only to converge their strategic interests and face China together – but also to make their bilateral relations resilient.”20

At the 10th meeting of foreign ministers held in Busan, South Korea, in November 2023, the three countries agreed to enhance cooperation in six areas, including people-to-people exchanges, economic collaboration, trade, and security. However, differences in their approaches to the triangle’s objectives prevented the planned trilateral summit from taking place by the end of 2023. For instance, during the meeting, Japanese and South Korean foreign ministers raised concerns about North Korea’s missile and nuclear capabilities, but their Chinese counterpart avoided addressing the issue altogether. At the previous trilateral meeting of foreign ministers four years earlier, Japan, South Korea, and China had reaffirmed close cooperation toward the complete denuclearization of the Korean Peninsula and full implementation of UN sanctions against North Korea. In Busan, however, the ministers only agreed to continue consultations at various levels to address the North Korean nuclear issue.

Trilateral summits in Northeast Asia are further hindered by unresolved bilateral issues. In Japan-China relations, a major sticking point remains Beijing’s ban on importing Japanese seafood due to Tokyo’s decision to release into the ocean treated wastewater from the Fukushima Daiichi Nuclear Power Plant that was damaged by an earthquake and tsunami in March 2011. Beijing distrusts Tokyo’s claims that the water has been fully decontaminated of radioactive materials. Meanwhile, Japan-South Korea relations were strained in late 2023 by another ruling from South Korea’s Supreme Court, requiring the Japanese government to pay compensation to “comfort women.” Tokyo maintains that this and other issues related to Japan’s colonial rule on the Korean Peninsula were resolved under a 2015 agreement between the two countries.

As Ryosuke Hanada asserts, the Japan-China-South Korea triangle, alongside the US-Japan-South Korea triangle, provides Tokyo and Seoul with a unique opportunity to meet annually with the leaders of both the US and China – a privilege no other nation have.21 Furthermore, as noted by the Japanese newspaper Asahi Shimbun, cooperation among Japan, China, and South Korea should not be limited to ensuring stability in Northeast Asia. Joint efforts should also address crises in other regions, such as Ukraine and Gaza.22

The future of the Japan-China-South Korea triangle will obviously depend in large part on the balance of centripetal and centrifugal forces shaping the relationships among these three major East Asian powers. In addition to the strengthened US-Japan-South Korea triangle established at Camp David, another potential triangle is emerging in the region: China-Russia-North Korea. This triangle is taking shape amid the intensifying deterioration of China-US relations in all areas, Russia’s military operation in Ukraine, unprecedented tensions on the Korean Peninsula, and growing hostilities surrounding Taiwan. Although some Western experts suggest that a China-Russia-North Korea triangle may lack cohesion, arguing that it does not serve Beijing’s interests because it could dilute China’s influence over Pyongyang, 23 the potential for enhanced military collaboration among these three states is a significant concern to Tokyo and Seoul. Japan’s Foreign Minister Yōko Kamikawa expressed alarm during her 2024 foreign policy address in parliament about the deepening military cooperation between China, Russia, and North Korea, which she said must be countered through collaboration with the US, South Korea, and other like-minded nations.24

* * *

The Camp David summit in August 2023, initiated by Washington, marked a critical step toward transforming the US-Japan-South Korea triangle into a fully-fledged military alliance. China’s growing naval activity in the South and East China Seas, coupled with its territorial ambitions, is increasingly seen by Washington, Tokyo, and more recently Seoul, as a direct threat to their national security. Furthermore, recent rising tensions surrounding Taiwan have been directly linked to the security concerns of not only Japan but also South Korea.

Key factors bolstering the role of the US-Japan-South Korea triangle as part of Washington’s Indo-Pacific strategy to contain China’s rising economic and military might include the 2022 election of South Korean President Yoon Suk Yeol – who seeks to elevate South Korea’s international stature across the Indo-Pacific region – and Tokyo’s accelerated efforts to build military strength and develop offensive capabilities, including the ability to strike targets on enemy territory. In addition to countering an assertive China, a primary goal of this trilateral alliance remains the elimination of North Korea’s missile and nuclear threat, a concern emphasized heavily by Tokyo and Seoul. The alliance also serves Washington’s goal of further involving its key Asian allies in the West’s proxy war with Russia in Ukraine.

A notable development within the revitalized triangle is the heightened focus on nuclear weapons. Washington and Seoul have agreed to deepen cooperation in deterring North Korea’s nuclear threats, as evidenced by recent military exercises near the Korean Peninsula involving a US B-52 bomber and the nuclear-powered aircraft carrier Carl Vinson. Meanwhile, Tokyo has begun discussing the possibility of extended nuclear deterrence (i.e., incorporating Japanese considerations) with the help of American nuclear weapons. This includes not only the nuclear weapons presumably stationed on US aircraft carriers and submarines that visit Japanese and South Korean ports but also those that could potentially be deployed on Japanese or South Korean territory. Despite these advances, historical tensions between Tokyo and Seoul remain a potential Achilles’ heel for the US-Japan-South Korea triangle.

Be that as it may, China, North Korea, and Russia – the primary targets of the US-Japan-South Korea alliance – are likely to prioritize coordination in response to this evolving framework. Their efforts to counter the triangle could be bolstered by closer collaboration within their own emerging geopolitical triangle in Northeast Asia.

NOTES:

1. Paramonov O. Kemp-Devid i ‘aziatskoye NATO,’ ” Mezhdunarodnaya zhizn, August 23, 2023, https://interaffairs.ru/news/show/41896 (retrieved on August 30, 2023); Reinkarnatsiya treugolnika SSHA – Yaponiya – Yuzhnaya Koreya, Valdayskiy klub, August 23, 2023, https://ru.valdaiclub.com/a/highlights/reinkarnatsiya-treugolnika (retrieved on February 8, 2024); “Why Joe Biden will host Japan and South Korea’s leaders at Camp David,” The Economist, August 10, 2023, https://www.economist.com/asia/2023/08/10/why-joe-biden-will-host-japan-and-south-koreas-leaders-at-camp-david (retrieved on February 11, 2024); Lee Ji-Young, Lim A. “Camp David: Institutionalizing Cooperation,” Comparative Connections, Vol. 25. No. 2 (September 2023), pp. 151-160, https://cc.pacforum.org/2023/09/camp-david-institutionalizing-cooperation-trilaterally/ (retrieved on February 12, 2024); Sneider D. “Japan-South Korea-US relations thawed, but not warm enough,” East Asia Forum, August 31, 2023, https://www.eastasiaforum.org/2023/08/31/japan-south-korea-us-relations-thawed-but-not-warm (retrieved on February 12, 2024).

2. Camp David Principles, The White House, August 18, 2023, https://www.whitehouse.gov/brief-ing-room/statements-releases/2023/08/18/camp-david-principles (retrieved on August 20, 2023); The Spirit of Camp David: Joint Statement of Japan, the Republic of Korea, and the United States, The White House, August 18, 2023, https://www.whitehouse.gov/briefing-room/statements-releases/2023/08/18/the-spirit-of-camp-david-joint-statement-of-japan-the-republic-of-korea-and-the-unitedstates (retrieved on August 20, 2023).

3. Lenhart E., Tkacik M. “Camp David summit paves way for potent trilateral alliance,” Asia Times, August 25, 2023, https://asiatimes.com/2023/08/camp-david-summit-paves-way-for-potent-trilateralalliance/ (retrieved on August 27, 2023).

4. Sneider D. “South Korea’s global geopolitical pivot,” East Asia Forum, January 15, 2024, https://www.eastasiaforum.org/2024/01/15/south-koreas-globalgeopoliticalpivot (retrieved on February 9, 2024).

5. See [3].

6. Quoted from: “Diplomatic Bluebook: Japan Must Actively Work for International Cooperation,” Yomiuri Shimbun, April 25, 2024, https://japannews.yomiuri.co.jp/editorial/yomiuri-editorial/20240425-182364 (retrieved on April 26, 2024).

7. See [3].

8. Okoshi Masahiro. “US, Japan, South Korea alliance sends clear message to China,” Nikkei Asia, August 20, 2023, https://asia.nikkei.com/Spotlight/Comment/U.S.-Japan-South-Korea-alliance-sendsclear-message-to-China (retrieved on September 22, 2023).

9. “Japan, US, S. Korea Conduct Joint Naval Drill,” Yomiuri Shimbun, January 18, 2024, https://japannews.yomiuri.co.jp/politics/defense-security/20240118–162968 (retrieved on January 19, 2024).

10. Dominguez G. “US, Japan and South Korea cooperation reaches new heights with aerial drill,” Japan Times, October 25, 2023, https://www.japantimes.co.jp/news/2023/10/25/japan/politics/us-japan-south-korea-military-cooperation (retrieved on January 10, 2024).

11. For more information, see: Kistanov V.O. “Japan and South Korea: Allies, Partners, Adversaries? The Anatomy of Relations,” Far Eastern Affairs, Vol. 48, No. 3 (2020), pp. 15-37.

12. Kim Haeyoon. “US, South Korea and Japan must give form to 3-way partnership,” Nikkei Asia, September 1, 2023, https://asia.nikkei.com/Opinion/U.S.-South-Korea-and-Japan-must-give-form-to-3way-partnership (retrieved on January 23, 2024).

13. See [12].

14. Lee Myunghee, Yang Sungik. “Embracing Japan makes Yoon less popular at home,” Asia Times, March 7, 2024, https://asiatimes.com/2024/03/embracing-japan-makes-yoon-less-popular-at-home (retrieved on March 7, 2024).

15. Yoon Young-kwan. “Deterrence is not enough in Northeast Asia,” Japan Times, September 3, 2023, https://www.japantimes.co.jp/commentary/2023/09/03/world/northeast-asia-deterrence (retrieved on February 23, 2024).

16. Yoon Young-kwan. “Deterrence is not enough in Northeast Asia,” Japan Times, September 3, 2023, https://www.japantimes.co.jp/commentary/2023/09/03/world/northeast-asia-deterrence (retrieved on February 23, 2024).

17. Hirohito Ogi. “How East Asia should prepare for a possible Trump comeback,” Japan Times, February 22, 2024, https://www.japantimes.co.jp/commentary/2024/02/22/world/east-asia-trump-comeback (retrieved on February 23, 2024).

18. Jesse J. “Japan’s former PM Aso meets Trump for talks on security and economy,” Japan Times, April 24, 2024, https://www.japantimes.co.jp/news/2024/04/24/japan/politics/aso-meets-trump (retrieved on April 25, 2024).

19. 日米韓首脳会談 力頼みの連携は危うい [Meeting of the leaders of Japan, the US, and South Korea. Cooperation based on force is dangerous,] 北海道新聞 [Hokkaido Shimbun], August, 20 2023, (retrieved on August 21, 2023)

20. Hanada Ryosuke. “CJK yields Japan-South Korea engagement with China,” East Asia Forum, January 4, 2024, https://eastasiaforum.org/2024/01/04/cjk-yields-japan-south-korea-engagement-with-china (retrieved on February 8, 2024).

21. See [20].

22. Japan, S. Korea, “China must work together to boost global stability,” Asahi Shimbun, November 28, 2023, https://www.asahi.com/ajw/articles/15068678 (retrieved on February 12, 2024).

23. Skylar Mastro Oriana. “The Next Tripartite Pact?” Foreign Affairs, February 19, 2024, https://www.foreignaffairs.com/china/next-tripartite-pact (retrieved on February 20, 2024).

24. “Japan foreign minister wants ‘mutually beneficial’ ties with China,” Japan Times, January 30, 2024, https://www.japantimes.co.jp/news/2024/01/30/japan/politics/japan-foreign-minister-policy-speech/ (retrieved on February 12, 2024).

Japan-US-South Korea Triangle: How Strong Will the New Alliance Be?