可以參考這連結：
https://www.state.gov/countries-areas/taiwan/#
其中說到
The U.S. 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 U.S. 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 U.S. will maintain cultural, commercial, and other unofficial relations with the people of Taiwan. The American Institute in Taiwan (AIT) is responsible for implementing U.S. policy toward Taiwan.

這單位的負責人，的確是真的~
https://zh.wikipedia.org/zh-tw/康達_(美國外交官)
看有沒有更專業的人解說