http://www.state.gov/r/pa/ei/bgn/35855.htm
U.S.-TAIWAN RELATIONS
The United States and Taiwan enjoy a robust unofficial relationship. The 1979 U.S.-P.R.C. Joint Communique switched diplomatic recognition from Taipei to Beijing. In the Joint Communique, the United States recognized the Government of the People's Republic of China as the sole legal government of China, acknowledging the Chinese position that there is but one China and Taiwan is part of China. The Joint Communique also stated that the people of the United States will maintain cultural, commercial, and other unofficial relations with the people on Taiwan. The American Institute in Taiwan (AIT) is responsible for implementing U.S. policy toward Taiwan.
The United States does not support Taiwan independence. Maintaining strong, unofficial relations with Taiwan is a major U.S. goal, in line with the U.S. desire to further peace and stability in Asia. The 1979 Taiwan Relations Act provides the legal basis for the unofficial relationship between the United States and Taiwan, and enshrines the U.S. commitment to assist Taiwan in maintaining its defensive capability. The United States insists on the peaceful resolution of cross-Strait differences, opposes unilateral changes to the status quo by either side , and encourages dialogue to help advance such an outcome.