Seoul's Silence: Why South Korea Cannot Afford to Take a Side on Taiwan
South Korea is an American treaty ally. It hosts 28,500 American troops, maintains one of the largest and most capable military forces in Asia, and has built its security architecture around the American alliance since the Korean War armistice of 1953. In any straightforward reading of alliance logic, Seoul should be a reliable partner in a Taiwan contingency. The reading is not straightforward. South Korea’s Taiwan position is defined by a set of structural constraints that make explicit commitment to Taiwan’s defense politically impossible in Korean domestic politics and strategically dangerous given Korea’s specific vulnerability profile.
The North Korea problem is the primary constraint. Any Korean participation in a Taiwan contingency that drew American forces away from the Korean peninsula, or that provoked Chinese retaliation against Korea, would occur against the backdrop of a North Korean military capability that includes nuclear weapons and ballistic missiles capable of reaching every major Korean city. A Korean government that committed forces or base access for a Taiwan operation would be making that commitment in a security environment where North Korea could use the resulting distraction — American forces engaged in the western Pacific, Chinese pressure applied to Korea as punishment — to pursue its own objectives on the peninsula. The Korean security situation is not separable from the Taiwan question in the way that the geography might suggest.
The China relationship adds the economic dimension that shapes Korean political calculations even more directly than the security concern. China is South Korea’s largest trading partner and the market for a disproportionate share of Korean electronics, automotive, petrochemical, and cultural exports. The THAAD missile defense deployment of 2017 demonstrated what Chinese economic retaliation against Korea looks like: restrictions on Korean cultural exports, boycotts of Korean products, and limitations on Chinese tourism to Korea that cost the Korean economy billions of dollars in a sustained pressure campaign that lasted approximately a year before a negotiated de-escalation. A Taiwan contingency that produced comprehensive Chinese economic retaliation against Korea would impose costs that Korean public opinion has demonstrated it does not want its government to incur.
The American bases in Korea are the source of the most acute dilemma. American forces at Osan, Kunsan, and other Korean facilities include assets — aircraft, logistics, command and control — that are relevant to a Taiwan contingency response. Whether these assets could be used for Taiwan operations would require Korean government authorization. The Status of Forces Agreement and the operational control arrangements for combined US-ROK forces complicate this question, but the political reality is that Korean bases cannot be used for operations that the Korean government has not authorized. A Korean government facing the constraints described above has limited political room to authorize Taiwan contingency operations from Korean soil.
The analytical conclusion is not that Korea would actively oppose American action in a Taiwan contingency, but that its support would be passive at best and that American operational planning for Taiwan cannot depend on Korean basing access or Korean military participation. This is a meaningful limitation. It means that the northern approach to the Taiwan Strait — through the East China Sea from Korean-hosted assets — is operationally constrained in ways that the southern approaches from Japanese and Philippine-hosted assets are not.
Korean public opinion on Taiwan has been surveyed and shows a population that is aware of the Taiwan issue, concerned about its implications, and deeply reluctant to see Korean involvement in what would be perceived as a great power conflict that Korea had no hand in precipitating. Democratic accountability in Korea, as in Taiwan itself, means that political leaders cannot commit to courses of action that their populations will not sustain. The Korean public will not sustain a Taiwan commitment that North Korean nuclear weapons make existentially risky and Chinese economic pressure makes economically painful.
The silence from Seoul is not ambiguity about values. It is a precise expression of the constraints that Korea’s geography imposes on its strategic choices.