President Bush stoked a new controversy on U.S.-China relations yesterday by saying unambiguously that the United States would do "whatever it took" to defend Taiwan in the event of a Chinese attack, even if that meant using U.S. military forces.

The stark declaration made on an ABC-TV morning show appeared to erase a 22-year-old U.S. policy of leaving unclear whether the United States would intervene to defend Taiwan. But the White House, while not retracting Bush's remarks, later scrambled to say that U.S. policy had not changed.

During a CNN interview a few hours after the ABC broadcast, Bush tempered his comments by reasserting U.S. support for a "one China" policy and opposing any declaration of independence by Taiwan, a democratic self-governing island of 23 million people that Beijing claims as part of China. Bush portrayed his comments as consistent with the 1979 Taiwan Relations Act and statements by previous administrations.

At the end of the day, it was unclear whether Bush had made a significant change in U.S. policy or had misspoken and did not want to acknowledge it. "The president is pleased to have said what he said and to have taken the stand that he took," White House spokesman Ari Fleischer said.

China policy experts said the president's initial comment went beyond earlier U.S. commitments and could further damage frayed relations with Beijing. There was no immediate reaction from Beijing, but even before Bush's comments, China's foreign ministry had "urgently summoned" U.S. Ambassador Joseph W. Prueher to protest the U.S. arms sale package for Taiwan and to warn that it would "seriously impact" China's cooperation on weapons proliferation.

"This clearly does go beyond what any previous administration has indicated either orally or in writing," said Kenneth Lieberthal, director of Asian affairs at the National Security Council during the Clinton administration. He said Bush's initial statement even went beyond a U.S.-Taiwan defense pact that was abrogated as one of the fundamental preconditions to establishing formal U.S. relations with Beijing in 1979.

Bush's remarks on ABC's "Good Morning America" came in response to a question about whether "you, in your own mind, feel that if Taiwan were attacked by China, do we have an obligation to defend the Taiwanese?"

Bush responded, "Yes, we do, and the Chinese must understand that. Yes, I would."

"With the full force of American military?" the interviewer asked.

"Whatever it took to help Taiwan defend herself," the president answered.

Jerome A. Cohen, a China legal expert and senior partner at the firm of Paul, Weiss, Rifkind, Wharton & Garrison, said that Bush's statement, "if taken literally, went beyond the Taiwan Relations Act, which says that action against Taiwan would be against American interests, but doesn't guarantee a response. . . . Here he was saying flat out, no ifs ands or buts. It was a startling statement."

Later, during a CNN interview, Bush said, "I have said that I will do what it takes to help Taiwan defend itself." But "at the same time, we support the one-China policy, and we expect the dispute to be resolved peacefully," he added. "Nothing has really changed in policy, as far as I'm concerned. This is what other presidents have said, and I will continue to say so," he said.

Although Bush cited the Taiwan Relations Act, it makes no promise of U.S. intervention. The law says the United States will supply "such defense articles and defense services in such quantity as may be necessary to enable Taiwan to maintain a sufficient self-defense capability." It also says, "It is the policy of the United States to maintain the capacity of the U.S. to resist any resort to force or other forms of coercion that would jeopardize the security or social or economic system of the people on Taiwan." Regarding the possibility of conflict, the act says that any action, boycott or embargo against Taiwan would be "a threat to the peace of the Western Pacific area and of grave concern to the United States."

Fleischer said "nothing in the act precludes the president from saying that the U.S. would do whatever it took to help Taiwan defend herself."

Condoleezza Rice, Bush's national security adviser, added that "the Taiwan Relations Act makes very clear that the U.S. has an obligation that Taiwan's peaceful way of life is not upset by force. What he said clearly is how seriously and resolutely he takes this obligation."

Traditionally, American administrations deliberately have left ambiguity about whether the United States would come to Taiwan's rescue if Beijing attacked. The mere possibility of U.S. intervention was considered sufficient to deter Beijing, while the absence of a promise to intervene was considered useful in preventing Taiwan from provoking Beijing with a declaration of independence.

Although the United States has always insisted on a peaceful settlement of differences across the Taiwan Strait, Beijing has refused to renounce the possibility of using force at some point.

Some policy analysts said that Bush's comment would alarm Beijing because many members of the Bush administration in the past have supported the scrapping of "strategic ambiguity."

Four administration members -- including Vice President Cheney's chief of staff and the deputy secretaries of state and defense -- signed a letter in late 1999 advocating just that.

In a November 1999 speech in Washington, Paul D. Wolfowitz, now deputy defense secretary, said that past U.S. policies of purposeful ambiguity have been misunderstood by adversaries and led to war. He cited Iraq in 1990 and North Korea in 1950 as examples.

"I don't believe that in the case of Taiwan today that anything is gained by leaving any doubt in the minds of Communist China that the use of force against Taiwan would be met with a strong American response," Wolfowitz said. He rejected the notion that defending Taiwan depended on circumstances, such was whether Taiwan had been provocative. "If we leave any ambiguity about that, all we are doing is encouraging Chinese actions that could get both of us in trouble," he said.

But Wolfowitz also said he would not advocate independence for Taiwan. "That would be unhelpful, to put it mildly," he said. He said self-governing, democratic Taiwan should be told that "what you have now is as good as independence."

Both Democrats and Republicans on Capitol Hill were left wondering whether the president was oblivious to the nuances of China policy, or intentionally changing it.

"The president made, I hope, an unintentional substantive mistake this morning," said Sen. Joseph R. Biden (Del.), the ranking Democrat on the Senate Foreign Relations Committee. "All presidents go through this, perhaps him more than others. It's important to get the detail down here. Words matter."

But the White House insisted that Bush got the words right. "It's the same policy, the same thing he said in the debate," said spokesman Scott McClellan. During a presidential debate in March last year, Bush took a tough stand but seemed conscious of the need to speak in veiled terms. "If China decides to use force, the United States must help Taiwan defend itself. Now the Chinese can figure out what that means, but that's going to mean a resolute stand on my part," he said.

Sen. John F. Kerry (D-Mass.) said on the Senate floor yesterday that Bush had abandoned the policy of "strategic ambiguity" with "absolutely no consultation with members of Congress or with our allies in the region." Kerry added, "We have been deliberately vague about the circumstances under which we would come to Taiwan's defense, not only to discourage Taiwan from drawing us in by declaring independence but also to deter a Chinese attack by keeping Beijing guessing."

Staff writers Dana Milbank and Thomas E. Ricks and correspondent John Pomfret in Beijing contributed to this report.