"With time, we'll find out that they did have a weapons program," Bush told reporters at the White House, dismissing suggestions that the nation's credibility is on the line.

"The credibility of this country is based upon our strong desire to make the world more peaceful - and the world is now more peaceful," he said. "The Iraqi people are now free."

Pressed by a reporter after a Cabinet meeting, Bush challenged the growing criticism that one of the primary U.S. premises for waging war against President Saddam Hussein and his Iraqi regime might have been based on faulty or doctored intelligence analysis.

Sunday, during a blitz of the morning news broadcasts, Secretary of State Colin L. Powell and White House national security adviser Condoleezza Rice faced similar questions and, in sometimes-forceful language, defended the prewar intelligence assessments.

"There's a very large body of evidence here that connects together to paint a picture of a very dangerous regime with very dangerous weapons that had deceived the world for 12 years, that had allowed international sanctions to stay on rather than come clean about what it was doing," Rice said on ABC's "This Week With George Stephanopoulos."

"Either you believe Saddam Hussein or you believe the overwhelming bulk of evidence," she said.

On Capitol Hill, several key members of Congress from both parties are calling for a thorough congressional inquiry.

Sen. Carl Levin, D-Mich., is contending that intelligence analysis appears to have been shaped politically. "There is significant evidence that the intelligence was shaded in order to support a policy, presumably of the administration," Levin said Monday on CNN.

Still, he said, it was "very likely" that the U.S.-led search in Iraq for evidence of biological, chemical or nuclear weapons programs would be successful.

"But that is a separate issue from whether or not the intelligence relating to those weapons was shaded to support a particular position," said Levin, the ranking Democrat on the Senate Armed Services Committee and a member of the Senate Intelligence Committee.

"If it was not a black-or-white issue, if it was a probability or possibility, that's what we should have been told," he said.

To buttress his contention, Levin cited three intelligence assertions by the Bush administration that have been questioned or discredited - that Iraq was acquiring aluminum tubes to develop nuclear weapons, that it was seeking uranium from Africa and that two semitrailers found in Iraq were, in fact, mobile laboratories to make biological agents.

"They make it into much more black and white than it really is," Levin said, referring specifically to the CIA.

In the months before the war with Iraq, Bush and his top aides, including Powell in a dramatic presentation to the U.N. Security Council on Feb. 5, made what they portrayed as a compelling case that Iraq had weapons of mass destruction and was continuing to develop them - and that Saddam should be disarmed, by force if necessary.

So far, though, U.S. military forces searching Iraq have found chemical protective gear, nerve gas antidotes and the two trailers - but no chemical, biological or nuclear weapons.

Now, U.S. combat forces are winding down their hunt, to be replaced by hundreds of other inspectors and analysts who the Bush administration thinks will be better suited to track down weapons.

Visiting U.S. troops in Qatar on Thursday, Bush repeated his assertion that the semitrailers could be used to make biological agents and vowed to "reveal the truth."

On Sept. 26, as he marshaled congressional support to use force against Iraq, Bush had said flatly in the White House Rose Garden: "The Iraqi regime possesses biological and chemical weapons. The Iraqi regime is building facilities necessary to make more biological and chemical weapons."

In his weekly radio address Oct. 5, Bush repeated his assertion and added: "Saddam Hussein has used these weapons of death against innocent Iraqi people, and we have every reason to believe he will use them again."

Earlier, however, the Defense Intelligence Agency had reported that there was no reliable evidence that Iraq was producing or stockpiling chemical weapons.

Asked to reconcile the differences, Fleischer told reporters Monday that the defense intelligence summary had been taken out of context from a larger report that he said "talks about how Iraq is distributing chemical weapons munitions."

History, Bush concluded, "will prove that the United States made the absolute right decision in freeing the people of Iraq from the clutches of Saddam Hussein."