A nation must think before it acts.
In a complex world there are few policy choices that carry all positive or all negative consequences for the security of the states involved.1 The decision facing the Republic of China on Taiwan (and the United States) about whether or not Taiwan should participate in the development and future deployment of theater missile defense (TMD) systems in East Asia is no exception. At present, the United States and Japan have initiated a long-term program to study, develop, and perhaps deploy sophisticated “upper-tier” missile defense systems in East Asia: ship-based navy theater-wide (NTW) and/or land-based theater high altitude air defense (THAAD). The question remains whether Taiwan, which is subject to missile threats from mainland China, ought to be included in the upper-tier program.