The July 2016 decision of South Korea to deploy Terminal High Altitude Area Defense (THAAD) triggered unprecedented retaliation from China even though Seoul and Washington conceded that THAAD could not protect the capital region of Republic of Korea (ROK). In a recent article, Yong Sub Choi analyses why the South Korean government decided to deploy THAAD anyway.
To answer this puzzle, it is necessary to connect the THAAD deployment in South Korea with the U.S. conception of a strategic rebalancing to Asia. Seoul’s THAAD decision was primarily intended to sustain and strengthen the U.S.-ROK alliance amid escalating nuclear threats by North Korea and deepening Sino-American rivalry. Placing the current state of the alliance at the center of its investigation into this controversial issue, the article pays particular heed to the ongoing adjustments being made between the two powers to better cope with the rise of China. Thus, by examining the underlying causes of the THAAD decision, it can also contribute to an understanding of the reconfiguration of the alliance amid the growing rivalry between the United States and China.
Conceptually, this article links South Korea’s decision to deploy THAAD with contemporary alliance politics in relation to extended deterrence and abandonment and entrapment risks. First, the deployment of THAAD on the peninsula itself may improve the security of South Korea by enhancing the credibility of U.S. extended deterrence through its contribution to the defense of U.S. territories and U.S. forces in East Asia and the western Pacific.
Second, the United States, following its rebalancing strategy, applied increasing pressure on South Korea to install THAAD on its soil, which decided to comply owing to much higher costs of abandonment of the alliance in the face of, most of all, possible nuclear attacks by North Korea. Technically, unlike what the South Korean government has publicly claimed, THAAD has only limited direct utility for the protection of South Koreans from North Korean missile. However, the THAAD deployment can contribute to its national security in a strategic way by reinforcing the U.S.-ROK alliance.
Once deployed on the Korean peninsula, THAAD can substantially enhance the credibility of U.S. extended deterrence by providing an additional layer of defense for U.S. territories and U.S. forces in East Asia and the western Pacific. The credibility of extended deterrence is determined by a complex mix of factors, where what counts is the degree of contribution by the client state to the national interest of the patron state. The deployment of THAAD in South Korea provides significant benefits for the United States, such that the former offers strategically important advantages to the latter, including enhanced protection of U.S. territories from North Korean and Chinese ICBMs and containing China’s military expansion in the South and East China Seas amid growing tensions between the two superpowers.
The wide gap in military capability between the United States and South Korea and the existence of North Korea have put the relationship between the two democracies on an asymmetrical footing, which required South Korea to adopt behaviors that were consistent with the former’s strategic interest, to a greater or lesser degree. The United States, following its rebalancing strategy, asked South Korea to side with it as it contained China’s military expansion with THAAD deployment as arguably the most important task for that ally at that moment. In the presence of escalating nuclear threats by North Korea, which heightened the costs of abandonment even further, South Korea decided to deploy THAAD, although it acknowledged that China would likely retaliate against South Korea for the decision. Seoul, showing a nuanced understanding of the alliance security dilemma, made this strategic choice because it believed that the costs of being abandoned by Washington surpassed those of being entrapped in conflicts with Beijing.
The most important strategic considerations for the United States at the global level involve dealing with or balancing China. By strengthening the U.S.-ROK alliance and providing its assistance to the United States to contain China’s military expansion, South Korea can bolster its status as a reliable ally, which is vital for taking the initiative in settling North Korean nuclear issue peacefully.
The growing tensions between the United States and China can bring harm to many countries’ national interests across the world. Nevertheless, it is rare to find countries, such as South Korea, which would so severely suffer both militarily and economically in the event of discord or conflict between the two superpowers. South Korea can contribute to improving strained relations between them only to a limited extent, but it can still minimize them, at least as regards North Korea’s nuclear weapons and missiles, by pursuing peace on the Korean peninsula in a manner that both sides can agree with.
If ongoing international efforts to put an end to North Korea’s nuclear and missile programs go awry, the tensions between the United States and China could be exacerbated even further. In that case, in response to U.S. demands, South Korea would not be able to avoid risking entrapment again in strife with China because of the nuclear threat that North Korea poses. Then, the degree of retaliation from China would be more severe than the one it imposed in the wake of South Korea’s decision to deploy THAAD in 2016.
Yong Sub Choi teaches at Seoul National University. He is the author of “Keeping the Americans in: The THAAD deployment on the Korean peninsula in the context of Sino-American rivalry”, Contemporary Security Policy, which is available here.