Taiwan_s foreign and defense policies have evolved greatly since the days of Chiang Kai-Shek. Its leaders have created a government based on popular sovereignty rather than Chinese nationalism; adopted pragmatic and creative approaches to expanding its international presence, and sought to make itself safe from attack or coercion by Mainland China through acquiring modern weapons, building a more efficient military, and developing closer military and political ties with the United States. China, in turn, has adopted a complex strategy of pressures and enticements to arrest Taiwan_s moves toward greater independence. The United States and Japan also wield substantial influence over Taiwan_s foreign and defense policies, but U.S. influence is clearly the dominant influence on Taiwan_s decisions about theater ballistic missile defenses-providing information and advice that will strongly shape the course of Taiwan_s planning, procurement, and deployment. The authors conclude that the United States should continue to maintain a public allegiance to the One China concept, combined with a posture of public ambiguity regarding the level of the U.S. defense commitment. Privately, the United States should make it clear to Beijing that it will respond militarily to a Chinese attack on Taiwan, and should state to Taipei that it will prevent a unilateral attempt to gain independence.