After eight months of fruitless search, George Bush has in effect washed his hands of the hunt for Iraq's weapons of mass destruction, in whose name the United States and Britain went to war last March.
David Kay, the CIA adviser who headed the US-led search for WMD, is to quit, before submitting his assessment to the US President in February.
The departure of Mr Kay, a strong believer in the case for toppling Saddam Hussein because of his alleged weapons, comes as a particular embarrassment to Tony Blair. This week he maintained that Mr Kay had uncovered "massive evidence" of a network of WMD laboratories.
For Mr Bush, the missing weapons are a politically charged issue. Pressed to explain why his administration had asserted Saddam possessed weapons, when at best fragmentary evidence of programs had been found, Mr Bush replied: "So what's the difference? "If he were to acquire weapons, he would be the danger," he said in an interview with ABC News' Diane Sawyer.
Mr Bush's public dismissal of the weapons issue is the latest move by Washington and London to change the justification for war. Weapons of mass destruction, and even weapons programs, are no longer being put forward as the reason for the invasion.
Senior US and British officials now dwell almost exclusively on the atrocities perpetrated by Saddam against his people, and the opportunity provided by his removal for a regeneration of the Middle East.
Opinion polls point to the strategy working. The US public has forgotten what it was being told every day only nine months ago about the "imminent threat" the former Iraqi leader posed to the US, while the capture of Saddam last Saturday had boosted the President's approval ratings to a healthy 60 per cent-plus.
Mr Kay's departure as head of the Iraq Survey Group (ISG) is said to be for family and personal reasons. He is not in Iraq at present but on holiday in Washington.
Mr Kay himself sounds increasingly doubtful that chemical or biological weapons will be found, and is said to be resentful that the US military was less than helpful to his experts, preferring to prioritize the counter-insurgency.
Publicly, Mr Kay insists, and points to his first interim report this autumn as proof, that the ISG has already unearthed evidence of ongoing weapons programs But he acknowledged on the BBC's Panorama program three weeks ago he was prepared to be proved wrong that no weapons existed.
Downing Street played down reports of Mr Kay's departure as "rumor, not fact", and denied that Mr Blair had given up hope that evidence of WMD would be found. Privately, British ministers cling to the hope of finding evidence of weapons programs rather than the actual chemical or biological weapons systems. They hope Saddam's capture will end the "climate of fear" among Iraqi scientists and enable them to be honest about his regime.
This week Mr Blair was accused by the Tories and Lib Dems of "spinning" the ISG's interim report after he said they had "found massive evidence of a huge system of clandestine laboratories, workings by scientists, plans to develop long range ballistic missiles".
The ISG, set up in June, has a nominal staff of 1,400 specialists, analysts and translators, all theoretically dedicated to the search for WMD. But the numbers in the field have been less: two teams of 20 at most. In October, the group's strength dwindled further when Donald Rumsfeld, the Defense Secretary, ordered many personnel to be transferred to the regular forces to help counter the growing rebellion.
Despite the capture and interrogation of many senior Iraqi officials, there has been no breakthrough. Saddam is said to have told investigators what Iraq told the UN before the invasion: that it no longer had banned weapons.
But the seizure of Saddam has given some American officials new hope that banned materials will be found.
Peter Kilfoyle, a former Defense minister, said Saddam's capture had not relieved the pressure on Mr Blair for weapons to be tracked down.
The former deputy chief UN weapons inspector Charles Duelfer said: "What is important is Saddam's intentions. The case can be made that he may not have had existing weapons, but his intention was to outlast the inspectors and reconstruct his weapons capabilities."