Bush has increasingly justified the war on Iraq, which he hinged on Saddam's possession of weapons of mass destruction, on liberating its people, even as he and top aides say the regime may have pre-emptively destroyed its arsenal.

"Perhaps over time we will find out what drove them to do that. Perhaps it was the fear of actually being discovered, caught red-handed with the very weapons we said they had," said White House spokesman Ari fleischer.

As clashes in Iraq become ever more sporadic, Bush may use a rare visit next Thursday to an aircraft carrier at sea, the USS Abraham Lincoln, to say the fighting is over but will stop short of declaring victory outright because key missions remain, said administration officials, who requested anonymity.

One reason for caution is that Bush sees a global picture still rife with challenges -- like setting Iraq on course for democracy and winning the global war on terrorism -- which make declaring victory premature, they said.

The US leader's speech will look beyond the military triumph in Iraq to those other efforts, said the officials, who refused to say precisely when Bush would speak but acknowledged that the carrier would be an ideal venue.

Bush remains confident that US-led forces scouring Iraq will find evidence of the weapons programs he placed at the core of his case for war, even though Baghdad always denied having them, said administration officials.

And he has repeatedly said that Saddam, whatever his fate since the war began March 19, is now irrelevant to Iraq's future, even as US forces seek to verify "some evidence" that the ousted leader was killed.

Fleischer said Friday that, "at the appropriate time," Bush will say "that the combat phase of the operation has come to a conclusion and that a new phase, the reconstruction of freedom, is beginning."

The US leader has repeatedly said he will only declare that the war is over when he hears that determination from the commander of US forces in the region, General Tommy Franks.

Such a message does not seem far off: The Pentagon declared April 14 that "major combat" was essentially over, and there have been few clashes of late involving US troops.

And Bush came close to saying things were wrapped up during a speech in Ohio on Thursday, declaring: "Now we have finished a war -- in the process of finishing a war in Iraq."

"The mission is not complete. Our forces still face danger in Iraq," added the president, who acknowledged that no conclusive evidence of Saddam's weapons has come to light since the invasion.

"But we know he had them, and whether he destroyed them, moved them or hid them, we're going to find out the truth," Bush said. "It's going to take time to find them."

In an interview with NBC television, he later said that interviews with captured Iraqis may yield damning evidence and said of Saddam: "Perhaps he destroyed some, perhaps he dispersed some."

"We have evidence now that we are gathering that shows that they may have destroyed some of them on the eve of the war -- they couldn't have destroyed them if they didn't have them," said Fleischer.

SPACE.WIRE