President Joe Biden said that the US would defend Taiwan if it were attacked, drawing sharp condemnation from China.
Mr Biden was pressed on the matter during a televised CBS interview on Sunday night after he evaded the question over whether Taiwan should be independent.
“But would US forces defend the island?” interviewer Scott Pelley asked him.
Mr Biden replied: “Yes, if in fact there was an unprecedented attack.”
Asked to clarify if he meant that, unlike in Ukraine, American forces would defend Taiwan if China invaded, Mr Biden answered: “Yes.”
Earlier in the interview, the president said he stood by the long-standing “One China” policy, under which the US does not have diplomatic ties with Taiwan and recognises it as part of China.
“We agree with what we signed on to a long time ago. And that there's the One China policy, and Taiwan makes their own judgments about their independence,” he said.
But China rebuked Mr Biden for his comments, claiming his words violated the policy.
“China strongly deplores and rejects it and has made solemn complaints with the US side,” Chinese Foreign Ministry spokeswoman Mao Ning said on Monday.
She also urged Washington not to “send any wrong signals” to Taiwan, saying that doing so would strain US-Sino relations even further.
“There is only one China in the world, Taiwan is part of China and the government of the People's Republic of China is the only legitimate government of China,” Ms Mao said.
A White House representative said US policy towards Taiwan has not changed.
“The president has said this before, including in Tokyo earlier this year. He also made clear then that our Taiwan policy hasn't changed. That remains true,” the representative told Reuters.
Relations between the US and China have grown increasingly fraught since House Speaker Nancy Pelosi visited Taiwan last month, with Beijing calling the trip a breach of the One China policy.
Agencies contributed to this report
