“The oldest and longest running of the United States’ deliberately ambiguous policies was whether and how it would defend the Republic of China on Taiwan in the event of an attack by the People’s Republic of China (Mainland China). This issue is at the cornerstone of United States–Taiwan relations and a central sticking point in United States–China relations. This policy was intended to discourage both a unilateral declaration of independence by ROC leaders and an invasion of Taiwan by the PRC.
“The United States seemingly abandoned strategic ambiguity in 2001 after then-President George W. Bush stated that he would ‘do whatever it takes’ to defend Taiwan. He later used more ambiguous language, stating in 2003 that, ‘The United States policy is one China.’
"In October 2021, President Biden announced a commitment that the United States would defend Taiwan if attacked by the People's Republic of China. But then the White House quickly clarified: ‘The president was not announcing any change in our policy and there is no change in our policy.’ In May 2022 Biden again stated that the U.S. would intervene military if China invaded Taiwan, though a White House official again stated that the statement did not indicate a policy shift.”