Biden says, again, that US would defend Taiwan from Chinese invasion

President Joe Biden said Sunday that the U.S. would militarily defend Taiwan if China were to attack -- reiterating, again, his support for the island as Beijing responded with disapproval.

In a "60 Minutes" interview, Biden was asked if "U.S. forces" would respond to aid Taiwan against China. He said, "If in fact there was an unprecedented attack."

He was asked again, "So unlike Ukraine, to be clear, sir, U.S. forces -- U.S. men and women -- would defend Taiwan in the event of a Chinese invasion?"

"Yes," Biden said.

His answer mirrors his response when another a reporter asked him a similar question during a press conference in Tokyo in May and is at least the fourth time he’s said something along these lines, appearing to go beyond the historic U.S. policy of “strategic ambiguity” about Taiwan's relationship to China, which views the island as a breakaway province despite Taiwan's separate government.

The U.S is legally required to provide Taiwan with resources to defend itself but doesn’t require a U.S. military response if China were to invade.

Since the '70s -- and as codified by the 1979 Taiwan Relations Act -- the U.S. has acknowledged the People's Republic of China as the sole legal government of China while officially considering Taiwan's status as unresolved and maintaining unofficial ties with the island, which emerged as a separate faction after the Chinese civil war.

At a Monday press conference in Beijing, Chinese government spokesperson Mao Ning said that China had lodged complaints with the U.S. in response to Biden's comments about Taiwan.

She said China "deplores" and "firmly opposes" the president's latest statements and that China reserves the right to take all necessary measures but said the country is "willing to do our best to strive for peaceful reunification."

In May, Biden said the "burden" of the U.S. "commitment" to defend Taiwan was "even stronger" after Russia's invasion of Ukraine earlier in the year.

Taiwanese Foreign Ministry spokesperson Joanne Ou said then that their government "expresses sincere welcome and gratitude to President Biden and the U.S. government for reiterating its rock solid commitment to Taiwan.”

A White House official insisted to ABC News at the time that Biden’s comment didn’t represent a shift because the president “reiterated our commitment … to provide Taiwan with the military means to defend itself.”

“The president has said this before, including in Tokyo earlier this year,” the official said. “He also made clear then that our Taiwan policy hasn’t changed. That remains true.”

In Tokyo, when a reporter asked Biden how the U.S. was prepared to respond if China were to invade or tried to take over Taiwan, the president first said, "Our policy toward Taiwan has not -- Taiwan -- has not changed at all."

But the reporter followed up, asking, "Are you willing to get involved militarily to defend Taiwan, if it comes to that?" Biden responded, "Yes." Asked, "You are?" he said, "That's the commitment we made."

The next day, asked if the policy of ambiguity toward Taiwan was "dead," Biden said, "No."

"The policy has not changed at all. I stated that when I made my statement yesterday," he said.

In July, after Biden and China's leader Xi Jinping spoke, a White House official said their discussion on Taiwan was “direct” and “honest,” with Biden reaffirming the U.S. commitment to its historic position. But the official wouldn’t respond to a Chinese readout claiming that Xi said, "Playing with fire will set yourself on fire.”

“President Xi used similar language in the conversation that the two leaders had back in November, but you know, I'm not going to get into parsing the various metaphors that the PRC regularly tends to use on these issues,” the administration official said.

ABC News' Justin Gomez and Karson Yiu contributed to this report.