Still harboring thoughts of retaking China, Jiang continued to plead for U.S. assistance. The Korean War (1950–1953) provided the first such chance, when Truman deployed the Seventh Fleet to the Taiwan Strait. Intervention by the People's Republic of China (PRC) in Korea in late 1950 quite suddenly made Taiwan a valuable strategic interest. The Republicans' victory in the 1952 U.S. presidential election further signaled American readiness to assist Jiang. In December 1953, Washington incorporated Taiwan into its defensive perimeter.
The need for a U.S.-ROC defense pact became apparent during the First Taiwan Strait Crisis (1954–1955). Following the Geneva Conference in April 1954, the United States worked closely with Southeast Asian nations to negotiate what later became the Southeast Asia Treaty Organization (SEATO) for collective security. Excluded from SEATO, Jiang proposed a bilateral mutual security pact between the United States and the ROC. Meanwhile, he took steps to strengthen the defense of Taiwan and its offshore islands. This precipitated the PRC's shelling of two island groups in the Taiwan Strait on 3 September 1954, sparking the First Taiwan Strait Crisis. The crisis hardened U.S. resolve to defend Taiwan. Thus, on 2 December 1954 the United States and the ROC signed the Mutual Security Treaty, formally acknowledging U.S.-ROC unity and pledging joint action against a common danger in Asia.
In return for U.S. support, the ROC granted America the right to station troops on Taiwanese soil. When the PRC seized the Dachens and Yijiangshan, another group of islands north of Taiwan in mid-January 1955, the U.S. Congress passed the Taiwan (Formosa) Resolution, authorizing the use of military force to defend Taiwan and its adjacent territory. The resolution committed American forces to Taiwan's defense, although it remained ambiguous whether the offshore islands were covered. The treaty and resolution were followed by considerable U.S. military, economic, and technical assistance to Taiwan, which helped in modernization efforts and maintained Jiang's GMD government. This solidarity, however, waned once the PRC and the United States began to normalize their relations in the early 1970s. On 1 January 1979 the United States severed its diplomatic relations with the ROC and terminated the treaty. The United States granted diplomatic recognition to the PRC in March 1979.
Still unwilling to abandon Taiwan completely, the U.S. Congress passed the Taiwan Relations Act in April 1979, which maintained an unofficial and nondiplomatic relationship with the Taiwanese regime.
Ross, Robert S., and Changbin Jiang, eds. Re-examining the Cold War: US-China Diplomacy, 1954–1973. Cambridge: Harvard University Press, 2001.; Tucker, Nancy Bernkopf, ed. Dangerous Strait: The U.S.-Taiwan-China Crisis. New York: Columbia University Press, 2005.