"The United States acknowledges the Chinese position that there is but one China and Taiwan is part of China. The United States Government will continue to maintain cultural, commercial, and other unofficial relations with the people of Taiwan.”
Taiwan Relations Act (1979): the U.S. law ensures continued unofficial relations with Taiwan and provides for arms sales and defense support.
Basically it is saying like "I hear your claim but I do not formally endorse or agree with your claim as a matter of us law or policy"
