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Since the establishment of the Republic of Korea in 1948, the Korean government has traditionally excelled at bilateral diplomacy centered on the United States and Japan. Around 1990, the world changed, ushering in an international order in which the Cold War structure collapsed. In short, the necessity of multilateral diplomacy became as pressing as that of traditional bilateral diplomacy. Nevertheless, considering that the ROK-U.S. alliance remains the most crucial diplomatic and security asset for a divided nation, multilateral forums addressing security issues were burdensome in many respects. Ultimately, APEC (Asia-Pacific Economic Cooperation), representing 40% of the world's population and 60% of global GDP, proved an exceptionally attractive stage. South Korea has actively participated in APEC activities since its founding in 1989, pooling wisdom with Australia, the United States, Canada, Japan, and others.

The key challenge now is how to effectively package and deliver the bundle of Korean diplomacy that was unpacked in Gyeongju during the 2025 APEC Summit. It is customary on the international stage that when major multilateral diplomacy unfolds, intense bilateral diplomacy unfolds simultaneously. President Lee Jae Myung is known to have held a total of 13 bilateral summit meetings during the APEC period. Among these, the second South Korea-U.S. summit since this administration took office and the South Korea-China summit with President Xi Jinping, visiting Korea for the first time in 11 years, hold particular significance. While it is difficult to summarize the outcomes and limitations in a single sentence, it is not an overstatement that the establishment of stable Korea-U.S.-China relations is the most crucial factor for the fate of the Korean Peninsula from the perspective of Korea's national interests. These Korea-U.S. and Korea-China summits presented important diplomatic agendas concerning issues on the Korean Peninsula, and North Korea's reaction to these agendas is likely to be highly complex.

First, President Lee Jae Myung and President Trump agreed―during their second summit since last August―to secure nuclear-powered submarines for South Korea. President Lee publicly requested the acquisition of fuels for nuclear-powered submarines from President Trump during the talks, and President Trump gave his final approval immediately after the summit. Initially, it was reported that President Trump's approval was contingent on the construction the submarines at a shipyard in Philadelphia. However, due to various practical issues, it is now understood that the South Korean and U.S. governments have reached an agreement to build them in South Korea. At the time, President Lee Jae Myung clearly stated in front of the South Korean public and media, “Diesel submarines have limitations in their submergence capabilities, making it difficult to track North Korean or Chinese submarines.” This was a statement that could have provoked open opposition from China and North Korea. However, the Chinese government appeared to defuse potential diplomatic friction by issuing a simple statement the next day expressing its hope that the NPT regime would be maintained in Northeast Asia.

The issue lies in North Korea's complex position and calculations. North Korea has yet to issue any statement on this matter. Presumably, it would find it difficult to identify a logical basis for publicly condemning the South Korean government. While China is a country whose nuclear possession is recognized within the NPT framework, North Korea is a case where it succeeded in developing nuclear weapons over the past 30 years by repeatedly violating the rules of the NPT system and engaging in numerous deceptions against the international community. The nuclear-powered submarine attempted by the South Korean government involves the military use of nuclear fuel. While this necessitates revising the Agreement for Cooperation concerning the Civil Use of Atomic Energy between South Korea and the United States, it still presupposes the carriage of conventional weapons. Therefore, it does not constitute a violation of obligations under the NPT regime. However, the successful operation of the submarine requires a stable supply of nuclear fuel. In this process, there is a possibility that the Korean government may request the United States to allow independent fuel production, leaving a complex negotiation process between South Korea and the United States ahead. North Korea, which is certainly aware of this entire process, must be deeply concerned about the potential loss of its exclusive monopoly on asymmetric weapons, which it has maintained through nuclear weapons. Nuclear-powered submarines clearly represent an asymmetric capability with significant symbolic meaning in a confined operational area like the Korean Peninsula.

Second, it is clear that the South Korea-China summit also presented North Korea with significant strategic challenges. Chairman Kim Jong Un visited China in early September for the Victory Day celebrations, appearing alongside President Xi Jinping at Tiananmen Square. Furthermore, the meeting between the leaders of North Korea, China, and Russia, alongside Russian President Putin, likely gave Pyongyang the impression that it had secured a highly meaningful diplomatic and security space. Yet, less than two months later, President Xi visited South Korea for the first time in 11 years. At the summit, the two nations pledged cooperation in future-oriented fields—including AI—to advance peace and prosperity not only for themselves but for the international community. Even if complex and delicate interests operate between North Korea and China, China has nonetheless been a steadfast pillar enabling North Korea to withstand international economic sanctions. Particularly during the 2018 U.S.-North Korea summit diplomacy, the leaders of North Korea and China met, remarkably, five times in a year and a half, deeply confirming their strategic cooperation. From North Korea's perspective, it had to watch the successful holding of the South Korea-China summit at a time when it believed the trilateral cooperation among North Korea, China, and Russia was stronger than ever before.

Third, the Gyeongju APEC meeting also hosted a summit between the U.S. and China. This too must have been a very unsettling situation for North Korea. Ultimately, the roles of the United States and China are crucial for resolving issues on the Korean Peninsula, including unification. Busan is the rightmost edge where the Eurasian continent begins, and simultaneously the leftmost edge where the Pacific Ocean begins. The fact that the leader of the continental giant China and the leader of the Pacific giant America met here seemed to symbolize Korea's fate caught between two superpowers. However, the U.S.-China summit held in Busan also demonstrated Korea's superior position vis-à-vis North Korea in resolving Korean Peninsula issues. A U.S.-China summit in Pyongyang is possible in theory, but in practice, it is difficult to imagine, at least for the foreseeable future. To reiterate, it is hardly an exaggeration that nearly all of Korea's national interests, including the North Korean issue, depend on successful ROK-U.S.-China relations.

Since the advent of modernity, every nation has set two goals: one being economic development, and the other, political development. Korea is no exception. Despite possessing only human resources as its capital, it has achieved successful economic growth and political development, representing over 50 Asian nations. Considering that over 80% of Korea's GDP is generated through trade, maintaining the liberal international order is critically important for Korea. From this viewpoint, the achievements secured by the Korean government through this Gyeongju APEC summit deem significant. Ultimately, the key lies in accurately analyzing North Korea's strategic calculations and pursuing successful diplomatic policies linked to this. After all, diplomacy is an extension of domestic governance, making the need for national wisdom for the post-APEC era all the more urgent. ■ 

■ Ihn-Hwi PARK is the Dean of the Graduate School of International Studies at Ewha Womans University.

■ Translated and edited by Inhwan OH, EAI Senior Research Fellow; Sangjun LEE, EAI Research Associate
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