Saddam should be given the chance to avoid a war that seems inevitable

To be credible, a UN ultimatum has to offer Saddam's regime a genuine way out if he chooses to take it

Seen through the headlines, it was all beginning to look pretty simple. The US was determined to go to war against Iraq and slowly, and in most cases reluctantly, the rest of the world was falling into line. There were some diplomatic preliminaries to come in New York, but America's fellow permanent members of the UN Security Council had been left in little doubt that while Washington would prefer their backing, it would go ahead without it ­ making it that much more likely that it would get the backing in the first place.

The Saudis ­ vital in the last Gulf War to the Allies' liberation of Kuwait ­ were already shifting towards acquiescence in a US invasion. The military build-up had begun. Military experts had started to talk "when" rather than "if", "how" rather than "whether". What could stop the war now?

Late last night it all suddenly looked a great deal more complicated. The announcement by the UN secretary general that Baghdad had agreed to unconditional UN weapons inspections has at the very least put all those assumptions in doubt.

As the small print of the Baghdad letter to the UN was digested in world capitals, the caution urged by Western politicians, the British Foreign Secretary Jack Straw among them, was understandable. Of course it could be another delaying tactic, another trick. Is the dictator of Baghdad really going to let the inspectors go exactly where they want to go? Is he really going to eschew the games he has played with them in the past?

But if it is at least the beginning of a real climbdown ­ and it's a big if ­ then it could yet raise important questions of what the war aims really are, and whether "regime change" is inherently one of them, irrespective of how Baghdad responds to the ultimatum that was being prepared for it in New York and irrespective of whether the latest signals are translated into real, unconditional admission of the weapons inspectors. If it is, then there is something essentially hollow about such an ultimatum.

If the concession is as big as Kofi Annan appeared to suggest in New York last night, then it is difficult, if not impossible, to see how the US could sustain a coalition for war against Iraq. Opposition to war within the Labour Party might well prove irresistible for many Labour MPs, as for many in European governments war has only been imaginable if President Saddam continues to resist an ultimatum on UN arms inspections. They have never shared in the enthusiasm for "regime change" in virtually any circumstances.

Equally it's possible that the new signals are no more than playing for time. But even if it is a mere delaying tactic there is still every reason for President Saddam's willingness to admit UN weapons inspectors to be tested to destruction.

For the casus belli to be clear, let alone legitimate, there has to be some hope, however modest, that the ultimatum can be met, even if that has not yet happened. And that may mean the odious Iraqi regime has to be given some reason for believing that there is some alternative, however unpalatable, to a war it almost certainly can't win; that "regime change", in other words, is not inevitable.

This appears to be understood even by America's staunchest and most uncritical ally, Britain. On the face of it, Mr Straw's weekend remarks in New York ­ pointedly using the term "regime change" ­ were as hawkish as it's possible to be. But he was careful both to insist that President Saddam had a "very clear choice" between being toppled and dealing with his weapons of mass destruction and to confine his explicit demands to the issue of such weapons. There have also been signs, within the interstices of Whitehall, of British concern that Baghdad is being given little reason ­ whether through "back channel" communication or any other means ­ for thinking that what would admittedly be an improbably dramatic rethink on his weapons of mass destruction (WMD) could yet save his skin.

International unease about all this had been increased by the terms in which President Bush framed his challenge to the UN last week. On one reading this reflected a victory for the Washington multilateralists over those, such as Dick Cheney and Donald Rumsfeld, who are seen as contemptuous of the UN and impatient to begin the war, almost whatever the circumstances. On another reading, however, the Bush speech was notable for its inclusion, in a long litany of the ills visited by Saddam, of issues going well beyond that of WMD ­ including support for terrorism, illicit trade and persecution of its civilian population. It's perfectly true that these issues are also covered by UN Security Council resolutions (though the large majority cover WMD). But they are a great deal less capable of verifiable fulfilment within the tightest of deadlines. As the former Australian Foreign Minister Gareth Evans wrote yesterday in the International Herald Tribune: " 'regime change' wasn't mentioned [in the Bush speech] but that's what it meant." According to one Whitehall voice, the resolution "needs to be tough enough to be credible, not so tough as to be incapable of being met". To include the other, non-WMD, breaches in the wording on a UN resolution is one thing. To link them directly to the ultimatum would be quite another.

This all matters hugely to European public opinion, not least in Britain where Parliament meets next week and the Labour conference looms the week after that. True, the signs are that opposition to war is diminishing. On the one hand, if President Saddam proves to have been smart enough to accept the Arab League's advice to admit the UN inspectors in accordance with Security Council resolutions, it would make it hard to the point of impossibility for the US to hold a war coalition together. Conversely, if public support is to be mobilised for war in Britain, let alone in the rest of Europe, not to mention the Muslim world, the dictator in Baghdad has to be seen to have a realistic opportunity to prevent it happening even if he hasn't done so already.

Tony Blair's minimum duty is surely to fight to ensure that happens. All the more so when the case that President Saddam is ready to use his weaponry has yet to be made. And when there is no evidence that his so far ill-defined support for international terrorism has anything to do with 11 September. And when oil increasingly looks to be at least a factor in the US targeting of Iraq. And when President Bush did not even mention, last week in New York, Israel's own breaches of UN resolutions (not to mention that three months after his 24 June speech on Israel-Palestine, he has yet to offer any realistic hope of even a framework for a negotiated settlement). And when the Allies are being asked to embark on a dangerous venture almost unprecedented in its dependence on the doctrine of pre-emption rather than retaliation. An ultimatum that clearly offers President Saddam's regime a way out, if he chooses to take it, may not be a sufficient condition for a just war against Iraq. But it is certainly a necessary one.