How Far Can South Korea-US-Japan Military Cooperation Go?

At a time of growing strategic competition between the U.S. and China and division among the international community after Russia's invasion of Ukraine, the core of America’s global strategy is solidarity with its allies. The logic is that protecting the current international order against China and Russia, the status quo-changing forces that challenge the liberal international order, can benefit all countries that share the same interests as the U.S. and should join together.

Cooperation between South Korea, the U.S. and Japan, which the United States has been devoting much effort to since Joe Biden took office, is part of the United States' global strategy. Since Yoon Suk-yeol took office, whose administration is very friendly to the United States, the United States has been tightening the reins of Korea-U.S.-Japan cooperation. Biden, who visited South Korea 10 days after the Suk-yeol’s inauguration, issued a joint statement emphasizing the importance of Korea-U.S.-Japan cooperation to strengthen the international order based on norms. Since then, South Korea, the United States and Japan have proceeded quickly with three-way talks. It took less than two months for the leaders of the three countries to meet in one place.

The U.S. wants military and security cooperation among South Korea, the U.S. and Japan, as it tries to expand and formalize existing but limited security with respect to joint military drills between South Korea, the U.S. and Japan.

Cooperation among Korea, the U.S. and Japan may be of strategic benefit to Korea, but it is also a formidable challenge, because it is very difficult to expand the scope of cooperation to the extent the United States is seeking. When talking about security cooperation between South Korea, the U.S. and Japan, South Korea points out that we need to respond to North Korea's nuclear and missile threats. However, the kind of security cooperation between the three countries that the United States is talking about goes far beyond the Korean Peninsula and Northeast Asia. The United States wants to utilize the military capabilities of South Korea and Japan, which are global military powers and key allies in Asia, in its Indo-Pacific strategy, and furthermore, in its global strategy. Just as the nature and goal of U.S. Forces Korea have expanded from responding to North Korean threats to deterring China's military expansion and stabilizing the Asian region, military cooperation between Korea, the United States and Japan will also extend beyond the Korean Peninsula as part of the U.S. global strategy. It is a completely different matter for South Korea, the U.S. and Japan to respond jointly to the North Korean nuclear issue and to cooperate militarily in the event of a U.S.-China conflict in the South China Sea or the Taiwan Strait.

The Korea-U.S.-Japan summit, held on the occasion of the NATO on June 29 illustrates well the countries’ respective thoughts on trilateral cooperation. President Biden emphasized cooperation for the common goal of the three countries. In particular, Biden drew attention by using the expression “trilateral engagement”.

We can infer that he has already conceived of a Korea-U.S.-Japan military alliance. On the other hand, President Suk-yeol's remarks focused on a joint response to North Korea's nuclear and missile threats and deepening the alliance with the United States. Japanese Prime Minister Kishida Fumio’s remarks revealed his intention to use trilateral military cooperation as a stepping stone in order to strengthen defense capabilities and change national security strategies in favor of becoming a military power.

It is not only the mismatch of perceptions among the three countries that makes it difficult to expand military cooperation between South Korea, the U.S., and Japan. There is a complex and subtle variable called Korea-Japan relations. It is not possible to elevate bilateral relations to a level where military cooperation is possible while overlooking problems that have not been solved for decades, such as the comfort women issue, the issue of compensation for victims of forced labor, and Japan's claim to sovereignty over Dokdo.

The Suk-yeol administration is rushing to improve Korea-Japan relations in order to keep pace with the U.S.-led rapidly progressing Korea-U.S.-Japan cooperation effort. It is for this reason that a public-private consultative body was formed to seek a solution to the issue of compensation for forced labor. However, this requires a sophisticated process and domestic support. A hasty effort at resolving this could create a political crisis for the Suk-yeol administration. Moreover, even if South Korea puts the fire out, it is a different matter to join hands militarily with Japan, which is essentially seeking to revise the peace agreement and become a military power.

Military cooperation between South Korea, the U.S., and Japan not only requires time, but has clear limitations. It is very difficult to achieve what the United States is asking for. Rather than overdoing it to keep pace with the U.S., it seems necessary to make a diplomatic effort to lower U.S. expectations and adjust the pace. Otherwise, not only will the U.S. fail to achieve the results it seeks, but both Korea-U.S. relations and Korea-Japan relations may suffer as a result.