Taiwan and the United States have maintained unofficial relations since 1979. The official relations between the government of the Republic of China on Taiwan and the federal government of the United States terminated due to the recognition of Beijing. The United States has relations with the 'people on Taiwan' with the Taiwan Relations Act. The Policy of deliberate ambiguity of US foreign policy to Republic of China is important to stabilize cross-strait relations and to assist ROC from PRC invasion if possible, whereas a policy of strategic clarity on Taiwan will induce PRC opposition and challenges US legitimacy in East Asia or beyond.