The weapons were never the best reason for war

If WMD had been the only reason, as Blair argued, there'd have been no cause for the war to proceed

Saddam's WMD were always a stupid reason for launching a war. Unlike many defenders of the conflict, I believed this before the weapons turned out to be phantoms, describing the WMD arguments a year ago as "a totally unconvincing lot of nonsense". The best case for the war was always that the Iraqi people wanted and needed an outside force to depose Saddam, because his tyranny was so vicious they couldn't do it themselves.

You don't have to believe that Bush was especially worried about human rights to support this argument: nobody seriously believes that the mass murder of Jews, gays and the disabled was the reason for British and American involvement in the Second World War, but it was the reason why much of the left rallied to the conflict.

The US administration's reasons for the war were complex, as Paul Wolfowitz, leading neo-con and Deputy Secretary of Defence, admitted in an interview with Vanity Fair. He explained, "For bureaucratic reasons we settled on one issue, weapons of mass destruction, because it was the one reason everyone could agree on." We will only know the full reasoning behind the war when the White House discussions are eventually declassified, but most of the factors hidden under the bureaucratic WMD umbrella are now in the public domain.

First, it was a projection of American power to ensure that other countries fell into line with US security demands. This much has worked: look at Iran and Libya's subsequent eagerness to disclose their nuclear programmes. Second, there was a real concern about Saddam developing WMD over time, not least because the sanctions regime was falling apart. The fact that he was sitting on so much of the world's much-needed oil supplies made this especially dangerous.

Third, the Americans were aware that their policy of fostering and supporting a culture of tyranny in the Middle East had bred psychotic political movements like al-Qa'ida. The political slum created by America had to be cleared, and Iraq seemed as good a place to start as any. Finally, the shifting of American troops to Iraq from Saudi Arabia, only possible because of the war, has ended the provocation of US troops on "holy soil" - thus ensuring that the key grievance voiced by Osama bin Laden has been dealt with. Any investigation into WMD has to be seen in this context. Yes, some ambiguities need to be cleared up, but WMD were always - at least in Washington - one factor among many.

At the moment, the history of Iraq's WMD is very murky in the public consciousness. Everybody acquainted with Iraq's recent history agrees the following facts to be true: Saddam Hussein had vast stockpiles of WMD in the 1980s and early 1990s (supplied by Thatcher, Reagan and Chirac, among others). In the "peace" imposed on the country in the aftermath of the 1991 Gulf War, Saddam was forced to dismantle his arsenal of weapons step by step, under the close watch of UN inspectors. He complied with the terms of that agreement until 1998, when the weapons inspectors left the country.

This is where the popular account of the recent past blurs. Why did Saddam stop disarming in 1998? Did he have any WMD left then, and if so, what happened to them? Any honest person has to acknowledge that the answers to these questions are not quite as mysterious as George Bush would have us believe.

The weapons inspectors left in 1998 for a fairly simple reason: Saddam discovered that the inspectorate had been infiltrated by the CIA, and was being used as a cover for US intelligence-gathering. Kofi Annan has condemned this vigorously. Once Saddam found out that the UN process was being used for spying, he froze the inspectors' activities, effectively forcing them to leave.

With the US and British armies on his doorstep in 2003, it seems that he began - in a curmudgeonly way - to co-operate with the inspectors again. His level of compliance was improving when the war was launched anyway, according to the chief UN weapons inspector, Hans Blix. If he had any WMD left between 1998 and 2003, he would have needed vast programmes to maintain them in a useable condition - and we would have found far more evidence of them after all this time. The truth is that any WMD he might have had left will be useless slush buried in the desert by now.

If WMD had been the only reason for the war, as Tony Blair has foolishly argued, then weapons inspections backed by the threat of force would have been the right tactic. There would have been no reason for the war to proceed when it did. (All opponents of the war should note that in this cosy scenario, the Iraqi people would have no possibility of democracy in their lifetimes, and would have the rule of Uday and Qusay Hussein to look forward to.) So, sure, have an investigation into how the intelligence services (France and Germany's included) misjudged the WMD situation. But without an honest explanation of why the war happened in the first place, it will be of little value.

j.hari@independent.co.uk