Weapons of mass destruction still haunt the Allies

International law and British and American credibility can only be restored if WMD are found

So that's it then. All over. The correspondents are packing their Baghdad bags and returning home. Jay Garner, the retired American general, is now in post in the manner of a colonial governor. The commercials have returned to Sky News. And when, on the BBC's Thursday night politics programme, Michael Portillo eventually discards the suit and tie that he has worn throughout the war for his preferred open-necked green shirt, we shall finally know that Iraq is yesterday's news. Then it will no doubt all become a big yawn, except for a few of the backbench rebels persisting with their inconvenient habit of asking awkward questions about weapons of mass destruction.

For the moment it seems that it is all just a matter of finding a few of the missing playing cards, re-connecting the electricity and water supplies and dusting down some spare ballot boxes, or shipping over some Florida voting machines. Democracy, Western-style, is then supposed to spread like a contagion throughout the Middle East. The infamous road-map will be published, and the lion of Israel will lie down with the lamb of Palestine.

Excuse me, however, if I am not awed by the sight of flying pigs. This war may have been a military success, but the "coalition allies" may yet find that they are hounded out of Iraq in ignominy, with public opinion here and in Baghdad forever regretting the day when we embarked on "nation-building".

Let us remind ourselves why it was that we were prepared to participate in the wrecking of the old world order that had endured for over 50 years. The UN, the EU and Nato have been destroyed as international forces of unity. And that because of the belief that unilateral action was the only way to neutralise a perceived threat from Iraq's weapons of mass destruction (WMD). Never was it supposed to be in the objective of either George Bush or our own Prime Minister to remove Saddam Hussein from power. All they wanted to achieve was disarmament – nothing more, nothing less. Such was the threat this tyrant posed to international security, and specifically to our own safety, that we could not even wait another few weeks for Hans Blix to complete his inspection.

But this nagging question of the existence of WMD will not go away – and nor should it be allowed to. The suspicion grows daily that even if Iraq possessed these weapons in the first place, they were certainly not available to support a last stand in Baghdad or Tikrit. It is therefore vital that MPs who stood their ground before hostilities and demanded evidence of WMD are not now browbeaten into submission.

There is a whiff of unpleasant triumphalism being used against the rebels who supposedly have been "proved wrong" and a determination to drive them into taking a Trappist vow of silence. But never has it been more urgent to re-visit the original reason for this conflict; the real test of the bravery of politicians will be whether they are prepared to ask the questions that Messrs Blair and Bush may never be able to answer.

Already the squirming by ministers such as Mike O'Brien at the Foreign Office indicates an unwillingness to be questioned by interviewers on the issue. But for a start, the Foreign Select Committee surely has an obligation to commence an inquiry into the issue. And however unpalatable it may be for the Government, Jeremy Corbyn is right to demand a thorough investigation by the Commons Intelligence and Security Committee concerning the intelligence given to the Government about WMD. The refusal of the British Government to contemplate such a suggestion cannot do anything but leave a lasting suspicion that "regime change" was really the only objective all along.

At best, after several dramatic announcements that turned out to be entirely false, yesterday's New York Times reported an assertion by a US military team that an Iraqi scientist, who claims to have worked for an Iraqi chemical weapons programme for more than a decade, said that Iraq destroyed chemical and biological warfare equipment only four days before the war began. The paper also says that the scientist alleged that some of the deadly agents were destroyed in the mid-90s, other stockpiles being sent to Syria. Evidence of Iraqi co-operation with al-Qa'ida is also claimed.

But if this report is to be credible, surely the Americans should hand over the scientist to the jurisdiction of the UN. Unsubstantiated assertions by the US military will merely fuel suspicions that the Americans are becoming ever more desperate to throw some minor titbit to Congress in order to forestall controversy if no credible evidence is found.

If Britain and the US now try to maintain that the removal of Saddam was justification in itself, and that the original war aims were superseded by events, they will never be trusted again by international opinion. The future of international law and British and American credibility in the rest of the Middle East, let alone with their Western partners, can only be restored if WMD are found. MPs who were persuaded only at the last minute to vote for military action already have some explaining to do to their constituency Labour parties. They should be first – even before Mr Corbyn – in asking the unanswered questions about WMD.

mrbrown@pimlico.freeserve.co.uk