David Clark: Mr Blair is in a state of confusion over this war

Tony Blair's response to the growing opposition to war has been to raise the stakes and provide yet another new justification for military action. As a million marchers assembled in London, he told Labour's spring conference that regime change in Baghdad was a supreme moral imperative: "Ridding the world of Saddam would be an act of humanity. It is leaving him there that is inhuman."

It is a position that leaves little room for interpretation. But until now the Government insisted that its objective was the disarmament of Iraq. Even President Bush was persuaded to agree the Blairite line that "regime change" could be redefined to include a change in the Iraqi regime's policies and not just a change of its personnel. From now on it will be difficult to reconcile anything short of Saddam Hussein's removal from power with a successful outcome for Mr Blair.

There are considerable risks involved in going down this route, and it is a mark of the Prime Minister's frustration with the hostile climate of public opinion that he has decided to take it. It is possible that it may even make matters worse. Every time a new set of arguments for marching on Baghdad is advanced, the greater the risk that it will look not so much like a reason as an excuse. It conveys a hint of desperation and a vague sense that the Government doesn't finds its own case terribly persuasive either.

First the justifications were based on the threat of weapons of mass destruction; then the emphasis changed to the links with al-Qa'ida. Now it's based on the oppression of the Iraqi people.

The problem for Mr Blair and George Bush is that there is an inverse relationship between the strength of these arguments successively deployed in support of action and the legitimacy each confers on the right to intervene in international law. The more compelling the evidence, the shakier the legal pretext.

For example, proof of Iraqi complicity in 11 September, or any of the numerous crimes committed by Osama bin Laden, would provide a cast-iron justification to act on grounds of self-defence alone. Unfortunately for the White House and Downing Street, the evidence of an Iraq/al-Qa'ida link is paper thin going on non-existent. For the past 18 months the resources of the most technologically proficient intelligence services in the world have been attempting to establish a connection.

The measure of their failure was the evidence Colin Powell detailed in his presentation to the Security Council. The terrorist chemical weapons factory he claimed to have identified in northern Iraq turned out to be nothing of the kind, and there is as yet no plausible explanation for why Saddam would wish to supply weapons of mass destruction to Bin Laden. He is not interested in lashing out for the sake of it. His purpose is to stay in power, something that could only be endangered by such an unstable alliance of opportunism.

The argument that Saddam continues to maintain an active weapons-of-mass-destruction programme is more credible, but not yet compelling. Hans Blix's objective judgement last week gave few grounds for a rush to war. The greatest cause for alarm concerns what we don't know; the proscribed chemicals, munitions and biological agents Iraq can't account for. Compliance with UN resolutions remains reluctant and far from complete. Saddam continues to behave like a man who has something to hide, and it is reasonable to assume, therefore, that he does have something to hide. But it is equally reasonable to insist that a war that will claim the lives of innocent people must be justified by a stricter evidential test than the balance of probability.

However, the moral case Mr Blair advanced at the weekend has the singular merit of being unanswerable. Anyone in any doubt only needs to log on to the Amnesty International website. The Prime Minister's problem is that, in and of itself, the unique brutality of the Iraqi regime provides no basis in law for intervention. For good or bad (and it is as much one as the other), the UN system is built on the principle of non-interference in the internal affairs of its members. There is an exceptional basis to intervene to prevent a grave humanitarian crisis, such as genocide or a massive and destabilising refugee movement of the kind we saw in Kosovo. But neither can be said to apply to Iraq.

The only way out of this dilemma is for Mr Blair to convince President Bush that a clear mandate from the UN is worth the wait and that the inspectors should be given the time they require. In exchange, he needs to extract from President Chirac a firm commitment to support a second resolution in the event that Saddam refuses to yield. He could call it the Third Way.

dkclark@aol.com

The author was a special adviser to Robin Cook as Foreign Secretary