After seven weeks of fruitless search, the Bush administration has come the closest so far to conceding that, contrary to its pre-invasion scaremongering, there may not have been any chemical or biological weapons in Iraq.
Several US military officers involved in the hunt in Iraq have raised the possibility that the illegal arms might have been destroyed, but the official line in Washington has been that Saddam Hussein had artfully hidden them, and sooner or later they would be found.
But now, Donald Rumsfeld, the Defence Secretary and one of the leading hawks on Iraq, has admitted that the weapons may not exist. "We don't know what happened," he told the Council of Foreign Relations in New York. "It is also possible that [Saddam's government] decided they would destroy them prior to a conflict."
What Mr Rumsfeld did not discuss was when the weapons might have been destroyed - immediately before the war, or long beforehand (as suggested by Iraqi defectors, who said as long ago as 1995 that they had been destroyed). Experts also doubt that, in the past few weeks or months, Iraq could have got rid of chemical and germ warfare stockpiles of the size alleged by Bush officials, without it being picked up by US and British intelligence.
Pentagon officials insist that Mr Rumsfeld broke no new ground and say that interrogations of senior Baathist officials and scientists will lead to the weapons' whereabouts. But his remarks may fuel the debate on whether the American public was sold the war on a false premise. As post-war reconstruction falters and US soldiers continue to die (four in recent days) at the hands of snipers and ambushers, questions are starting to be asked.
On Capitol Hill, in particular, scepticism is growing, despite a reluctance by Democrats to challenge Mr Bush on a national security issue that plays to a popular President's strengths. "This could conceivably be the greatest intelligence hoax of all time," said Jane Harman of California, the senior Democrat on the House intelligence committee.
The quality of the intelligence is to be looked at by a CIA-led team. This was suggested as long ago as October, with the aim of monitoring the process leading up to a war in Iraq, which even then seemed likely.
Intriguingly, the prime instigator of the investigation was Mr Rumsfeld who, disappointed by the lukewarm findings of the CIA, set up an intelligence unit inside his office to assess the Iraq threat. This body is known to have relied heavily on information provided by the Iraqi National Congress exile group, led by Ahmed Chalabi, long the preferred choice of the Pentagon and the Vice-President, Dick Cheney, to lead post-Saddam Iraq.
Whether the initiative will uncover the truth remains to be seen. The involvement of Mr Rumsfeld has been memorably likened by Maureen Dowd, the New York Times columnist, to "O J [Simpson] vowing to find the real killers" of his wife.
Even so, the controversy is unlikely to assume the proportions it has in Britain unless Iraq descends into anarchy and substantial numbers of US troops are lost. At present, complaints are directed at the shortcomings of the Pentagon's post-war planning, and the inadequate number of American soldiers in Iraq to restore order.
More than 100,000 troops are said to be in the country. But experts say at least double that will be needed. Weeks before the war, General Eric Shinseki, the outgoing army chief of staff, told a congressional panel that "several hundred thousand" troops would be required to keep the post-war peace. General Shinseki was slapped down by Paul Wolfowitz, the Deputy Defence Secretary, as "way off the mark". But he may have been right.
The claims that paved the path to the invasion of Iraq
30 January, 2002. George Bush: "The Iraqi regime has plotted to develop anthrax and nerve gas and nuclear weapons for over a decade ... This is a regime that has something to hide from the civilised world. States like these, and their terrorist allies, constitute an axis of evil, arming to threaten the peace of the world."
State of the Union address
24 September, 2002. Tony Blair: "I have been increasingly alarmed by the evidence from inside Iraq that ... despite his denials, Saddam Hussein is continuing to develop weapons of mass destruction, and with them the ability to inflict real damage upon the region, and the stability of the world."
Foreword to 'Iraq's weapons of Mass Destruction: The Assessment of the British government'
8 November, 2002. George Bush: "If Iraq fails to fully comply, the United States and other nations will disarm Saddam Hussein."
On the UN Security Council backing resolution 1441
8 November, 2002. Tony Blair: "Conflict is not inevitable, but disarmament is ... everyone now accepts that if there is a default by Saddam the international community must act to enforce its will."
5 February, 2003. Colin Powell: "One of the most worrisome things that emerges from the thick intelligence file ... is the existence of mobile production facilities used to make biological agents ... The trucks and train-cars are easily moved and are designed to evade detection ... in a matter of months, they can produce a quantity of biological poison equal to the entire amount that Iraq claimed to have produced in the years prior to the Gulf War."
Addressing the UN Security Council
5 February, 2003. Colin Powell: "Our conservative estimate is that Iraq has a stockpile of between 100 and 500 tons of chemical weapons agent. That is enough to fill 16,000 battlefield rockets. Even the low end of 100 tons of agent would enable Saddam Hussein to cause mass casualties across more than 100 square miles of territory, an area nearly five times the size of Manhattan."
5 February, 2003. Colin Powell: "Let me remind you ... of the 122mm chemical warheads the UN inspectors found. This discovery could well be ... the tip of a submerged iceberg. The question before us all is when will we see the rest of the submerged iceberg?"
14 February, 2003. Hans Blix: "Since we arrived in Iraq, we have conducted more than 400 inspections of more than 300 sites. All inspections were performed without notice, and access was almost always provided promptly. In no case have we seen convincing evidence that the Iraqi side knew in advance that the inspectors were coming."
Addressing the UN Security Council
27 February, 2003. George Bush: "In Iraq, a dictator is building and hiding weapons that could enable him to dominate the Middle East and intimidate the civilised world, and we will not allow it ... Acting against the danger will also contribute greatly to the long-term safety and stability of our world."
Address at the American Enterprise Institute in Washington
18 March, 2003. George Bush: "Intelligence gathered by this and other governments leaves no doubt that the Iraqi regime continues to possess and conceal some of the most lethal weapons ever devised."
Televised address, giving Saddam Hussein 48 hours to leave Iraq or face war
18 March, 2003. George Bush: "The danger is clear: using chemical, biological or, one day, nuclear weapons obtained with the help of Iraq, the terrorists could fulfil their stated ambitions and kill thousands or hundreds of thousands of innocent people in our country or any other."
20 March, 2003. George Bush: "At this hour, American and coalition forces are in the early stages of military operations to disarm Iraq, to free its people and to defend the world from grave danger."
Televised address, announcing the start of the war
20 March, 2003. Tony Blair: "Our choice is clear: back down and leave Saddam hugely strengthened or proceed to disarm him by force."
Address to the nation as war started
2 April, 2003. Jack Straw: "The removal of Saddam Hussein's regime has become necessary to eradicate the threat from his programmes to develop weapons of mass destruction."
Speech at a Newspaper Society lunch
22 April, 2003. Hans Blix: "The US was very eager to sway the votes in the Security Council, and they felt stories about these things would be useful to have, and they let it out. And thereby they tried to hurt us a bit and say we had suppressed this. It was not the case, and it was a bit unfair, and hurt us."
Hans Blix, telling the BBC the US had seized on his alleged failure to include details of a drone and cluster bomb found in Iraq, in his presentation to the Security Council before the war
24 April, 2003. Jack Straw: "Given the fact that it will be American and British military who will be first on to any site, it will always be possible for those who opposed this military action to say, 'Oh well, they were planted'. Now, they won't be planted. We're going to immense care to ensure the veracity of the finds."
Speaking on the BBC News Interactive's 'Talking Point'
28 April, 2003. Tony Blair: "There was a six-month campaign of concealment of those weapons ... Before people crow about the absence of weapons of mass destruction, I suggest they wait a little bit."
Monthly news conference at 10 Downing Street
14 May, 2003. Jack Straw: "I hope there will be further evidence of literal finds ... It [Iraq's illegal arsenal] certainly did exist. There is no question about that ... It's not crucially important."
Interviewed on the BBC 'Today' programme
23 May, 2003. Hans Blix: "I am obviously very interested in the question of whether or not there were weapons of mass destruction and I am beginning to suspect there possibly were not ... It may turn out that in this respect the war was not justified."
In an interview with the Berlin newspaper, 'Der Tagesspiegel'
28 May, 2003. Donald Rumsfeld: "It is also possible that they decided they would destroy them prior to a conflict... It's hard to find things in a country that's determined not to have you find them. I suspect we'll learn a lot more as we go along and keep interrogating people."
In a speech in New YorkReuse content