中美共同防禦條約
Initially, the United States abandoned the KMT and expected that Taiwan would fall to the Communists. However, in 1950 the conflict between North Korea and South Korea, which had been ongoing since the Japanese withdrawal in 1945, escalated into full-blown war, and in the context of the Cold War, US President Harry S. Truman intervened again and dispatched the US Navy's 7th Fleet into the Taiwan Strait to prevent hostilities between Taiwan and mainland China. In the Treaty of San Francisco and the Treaty of Taipei, which came into force respectively on 28 April 1952 and 5 August 1952, Japan formally renounced all right, claim and title to Taiwan and Penghu, and renounced all treaties signed with China before 1942. Neither treaty specified to whom sovereignty over the islands should be transferred, because the United States and the United Kingdom disagreed on whether the ROC or the PRC was the legitimate government of China. Continuing conflict of the Chinese Civil War through the 1950s, and intervention by the United States notably resulted in legislation such as the Sino-American Mutual Defense Treaty and the Formosa Resolution of 1955.