The defense leaders of the United States, South Korea, and Japan took the historic step of institutionalizing trilateral security cooperation by signing a “Memorandum of Cooperation on the Trilateral Security Cooperation Framework [TSCF]” in Tokyo on July 28. This memorandum builds on the Trilateral Leaders’ Summit at Camp David in August 2023, which stipulated, inter alia, regularizing various forms of trilateral cooperation. It is the latest move by Washington, Seoul, and Tokyo to deepen and expand ties amid increasing volatility in the regional security environment, with rising threats from China and North Korea and growing concerns about Russia’s strengthened relations with North Korea.
The memorandum, while not a legally binding document, is nonetheless significant for normalizing specific areas of trilateral security cooperation, such as senior-level policy consultations, information sharing, and trilateral exercises. It also paves the way for the three nations’ security cooperation to address concerns outside of the region: The meeting’s joint statement stipulates “peace and stability on the Korean Peninsula, in the Indo-Pacific region, and beyond.”
For South Korea, the memorandum is a diplomatic triumph for President Yoon. It is the realization of a proposition made earlier this year to codify trilateral security cooperation in a joint document. Moreover, it provides an insurance plan of sorts against potential policy reversals due to leadership changes in Japan and the United States, which have major elections coming up in September and November, respectively. The memorandum is consistent with Yoon’s push to play a more active role on the global stage, encapsulated by its “global pivotal state” initiative, and provides a tangible win for his foreign policy strategy, which has unequivocally prioritized Seoul’s alliance with the United States and taken a forward-leaning position on security cooperation with Japan.
Although the memorandum marks a major milestone in US-South Korea-Japan trilateral security cooperation, it is not without challenges and potential limitations. First, the general assessment is that South Korea’s threat perceptions and strategic priorities differ from those of the United States and Japan. For Seoul, North Korea is the top security threat. For Washington and Tokyo, however, China is the main priority. This could strain the security cooperation unless the three countries effectively manage their differences.
Second, the memorandum is not legally binding. While this is a meaningful effort to institutionalize trilateral security cooperation, it may not survive leadership changes in the United States, South Korea, or Japan. Trump, if reelected, is unlikely to continue what the Biden administration has built. For instance, in the past he complained about the high costs of US-South Korea joint military drills, or what he called, “war games.” Seoul-Tokyo relations, fraught with historical and territorial issues, are heavily susceptible to domestic politics. This is particularly true in South Korea, where military cooperation with Japan historically has been a sensitive issue. Yoon and Japanese Prime Minister Kishida were able to mend ties for now, ushering in what some pundits have called a “honeymoon.” Even the latest public survey by the South Korean Defense Ministry shows that 80.5 percent of South Koreans support stronger trilateral security cooperation to counter North Korea’s threat. Yet, this relationship always has the potential to deteriorate even in the best of times, which in turn can affect the implementation of the memorandum.
As of July 31, North Korea has yet to react to the trilateral ministerial meeting or the adoption of the memorandum. However, it has issued a steady stream of media commentary and official statements in recent years on the strengthening of US-South Korea-Japan trilateral security cooperation, which offers a good barometer of Pyongyang’s anticipated line of criticism. Most notably, one article published in the authoritative Party daily in early July warned that the institutionalization of US-South Korea-Japan trilateral security cooperation would result in “further aggravating the situation in the Asia-Pacific region and bringing about a nuclear crisis.” This article built on an earlier North Korean Foreign Ministry statement, which notably went beyond accusing the United States, South Korea, and Japan of forming a “tripartite military bloc” and hinted that it would step up “mutual cooperation and concerted action” with other countries—almost certainly including Russia—to establish a “structure” capable of deterring it.
For the United States, South Korea, and Japan to successfully achieve the intended goal of the memorandum of understanding—contribute to peace and stability—they should also make efforts to minimize room for miscalculation or misjudgment by China or North Korea, for example by making continued efforts toward communication.
An Insurance Plan for Peace: Trilateral Security Pact Between South Korea, US, and Japan
By Rachel Minyoung Lee
Korean Peninsula
The defense leaders of the United States, South Korea, and Japan took the historic step of institutionalizing trilateral security cooperation by signing a “Memorandum of Cooperation on the Trilateral Security Cooperation Framework [TSCF]” in Tokyo on July 28. This memorandum builds on the Trilateral Leaders’ Summit at Camp David in August 2023, which stipulated, inter alia, regularizing various forms of trilateral cooperation. It is the latest move by Washington, Seoul, and Tokyo to deepen and expand ties amid increasing volatility in the regional security environment, with rising threats from China and North Korea and growing concerns about Russia’s strengthened relations with North Korea.
The memorandum, while not a legally binding document, is nonetheless significant for normalizing specific areas of trilateral security cooperation, such as senior-level policy consultations, information sharing, and trilateral exercises. It also paves the way for the three nations’ security cooperation to address concerns outside of the region: The meeting’s joint statement stipulates “peace and stability on the Korean Peninsula, in the Indo-Pacific region, and beyond.”
For South Korea, the memorandum is a diplomatic triumph for President Yoon. It is the realization of a proposition made earlier this year to codify trilateral security cooperation in a joint document. Moreover, it provides an insurance plan of sorts against potential policy reversals due to leadership changes in Japan and the United States, which have major elections coming up in September and November, respectively. The memorandum is consistent with Yoon’s push to play a more active role on the global stage, encapsulated by its “global pivotal state” initiative, and provides a tangible win for his foreign policy strategy, which has unequivocally prioritized Seoul’s alliance with the United States and taken a forward-leaning position on security cooperation with Japan.
Although the memorandum marks a major milestone in US-South Korea-Japan trilateral security cooperation, it is not without challenges and potential limitations. First, the general assessment is that South Korea’s threat perceptions and strategic priorities differ from those of the United States and Japan. For Seoul, North Korea is the top security threat. For Washington and Tokyo, however, China is the main priority. This could strain the security cooperation unless the three countries effectively manage their differences.
Second, the memorandum is not legally binding. While this is a meaningful effort to institutionalize trilateral security cooperation, it may not survive leadership changes in the United States, South Korea, or Japan. Trump, if reelected, is unlikely to continue what the Biden administration has built. For instance, in the past he complained about the high costs of US-South Korea joint military drills, or what he called, “war games.” Seoul-Tokyo relations, fraught with historical and territorial issues, are heavily susceptible to domestic politics. This is particularly true in South Korea, where military cooperation with Japan historically has been a sensitive issue. Yoon and Japanese Prime Minister Kishida were able to mend ties for now, ushering in what some pundits have called a “honeymoon.” Even the latest public survey by the South Korean Defense Ministry shows that 80.5 percent of South Koreans support stronger trilateral security cooperation to counter North Korea’s threat. Yet, this relationship always has the potential to deteriorate even in the best of times, which in turn can affect the implementation of the memorandum.
As of July 31, North Korea has yet to react to the trilateral ministerial meeting or the adoption of the memorandum. However, it has issued a steady stream of media commentary and official statements in recent years on the strengthening of US-South Korea-Japan trilateral security cooperation, which offers a good barometer of Pyongyang’s anticipated line of criticism. Most notably, one article published in the authoritative Party daily in early July warned that the institutionalization of US-South Korea-Japan trilateral security cooperation would result in “further aggravating the situation in the Asia-Pacific region and bringing about a nuclear crisis.” This article built on an earlier North Korean Foreign Ministry statement, which notably went beyond accusing the United States, South Korea, and Japan of forming a “tripartite military bloc” and hinted that it would step up “mutual cooperation and concerted action” with other countries—almost certainly including Russia—to establish a “structure” capable of deterring it.
For the United States, South Korea, and Japan to successfully achieve the intended goal of the memorandum of understanding—contribute to peace and stability—they should also make efforts to minimize room for miscalculation or misjudgment by China or North Korea, for example by making continued efforts toward communication.
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