Abstract

This paper aims to examine the US –South Korea alliance from the perspective of the “Autonomy –Security Trade ‐off” (AST) model, which was introduced by Michael F. Altfeld in the 1980s. This model could be a useful tool to ascertain the minimum conditions for the implementation of the US nuclear umbrella, which is a life ‐and ‐death issue for South Korea (ROK) given the serious North Korean nuclear threat. For this purpose, this paper introduces the key concept of the model and applies it to the ROK ‐US alliance, analyzing the controversy over the deployment of the US Terminal High Altitude Area Defense system (THAAD) to South Korea as a case study. The analysis found that South Korea started its alliance with the United States based on the AST model. However, South Korea became reluctant in yielding its autonomy to the United States in the 1990s, and initiated “balanced diplomacy” between the United States and China and the reclaiming of the Operational Control Authority (OPCON) from the commander of the ROK ‐US Combined Forces Command (CFC), a US General, in the 2000s. It delayed the deployment of the US THAAD for 3  years only because China opposed the deployment even after North Korea had succeeded to develop its nuclear weapons. However, South Korea had to return to the original AST model, albeit reluctantly, because of the emergence of a more serious North Korean nuclear threat, including hydrogen bombs. It did not try, with any great effort, to improve its relationship with China, and reduced the scope of OPCON by appointing a South Korean General as the Command of the CFC, allowing the deployment of the THAAD. Now that North Korea has the potential capabilities to strike the US mainland, South Korea cannot afford to be reluctant in yielding its autonomy to the United States. In this context, South Korea should not pursue its balanced diplomacy between the United States and China any longer. To the contrary, it should participate in the United States’ Indo ‐Pacific strategy. It may also need to stop its pursuit of appointing its general as the Commander of the CFC until North Korea gives up its nuclear weapons. It should also become more willing to increase its cost ‐sharing with the United States. In conclusion, South Korea should try to accept the recommendations from the AST model as long as its needs the US nuclear umbrella and wants to protect its people from the North Korean nuclear threat.