Blair is still shoulder to shoulder with President Bush - but for how long?

You don't have to like a single thing about Donald Rumsfeld to recognise he is a an interesting and unusual politician. While most people in his line swiftly learn the art of self-censorship, Rumsfeld's mouth is directly connected to his brain. It's a big part of why he is a rather effective communicator. Most politicians, asked a good question, will automatically say a good deal less than they know, just to be on the safe side. Rumsfeld tends to give a straight answer unless there is a very pressing and obvious reason not to.

Which is why I find it difficult to buy into the "Rumsfeld was just being Rumsfeld trying to be helpful and totally screwing it up" explanation of what he said at his Washington press conference on Tuesday about the possibility of the US going to war without the UK in the absence of a second UN resolution. It may have been tactically unwise to exhibit – not least to Baghdad – problems at the core of the coalition. It was hardly helpful to Tony Blair to read that the US Defence Secretary was offering him an "exit route". And it may have been very badly timed, hindering efforts to secure a second UN resolution today or tomorrow.

But that doesn't mean Mr Rumsfeld was necessarily fantasising. Is it possible that he had been warned that very day on a secure line by his British counterpart, Geoff Hoon, that this is where Britain and its Parliament might end up if there is no second resolution? Or, if not, that he had heard some other intelligence from London and, in response to a question at the press conference, laid out the situation as he understood it? And that the genuine shock at Number 10 on Tuesday evening wasn't so much at what Mr Rumsfeld had said but at the fact he had spoken about it at all?

For as soon as you think about it, you realise it would be extraordinary, not to say hugely, wilfully, irresponsible if the option of not sending British troops into combat in the absence a UN resolution were not at least being considered. For all the efforts by some of his critics to depict him as a wild-eyed warmongering zealot, Mr Blair, a leader at the peak of his powers (as anyone in the Commons yesterday could see) has not taken leave of his senses. No prime minister, let alone an internationalist Labour prime minister, would do other than think long and hard before risking the lives of British troops in such circumstances. And that's before you consider the parliamentary risks. Or that only 19 per cent of Britons favour action without a fresh UN resolution in the latest opinion poll.

There is a distinction here that isn't always made. If a majority on the Security Council voted for military action, but the resolution was then vetoed by the French, that would probably be the sort of "unreasonable" veto that Mr Blair has long indicated he would be prepared to ignore. But what if the resolution fails to get a majority this week before we even get to a threatened veto? Mr Blair's body language yesterday was enough to convince many people that he would still decide to go it alone – and for all the brave talk about Italy, Spain, Denmark and the East Europeans, that's what it would mean militarily – with the Americans. It's not chauvinist to say that the absence of British troops might lengthen the war. But this, surely, does not mean that the option of doing exactly as Mr Rumsfeld suggested isn't under consideration in Whitehall's inner recesses. Particularly, if the law officers are showing any queasiness about the prospects. And if it isn't, it certainly should be.

For if a majority of the Security Council votes no, despite the extraordinary arm-twisting by the US, it may well be the only correct course – politically, morally and, perhaps, legally – to follow in practice. Of course, there would be a political downside for Mr Blair because of the determination he has personally shown to disarm Saddam. A combination of pro-US rhetoric and a failure to send a single British soldier to the theatre was what made life so uncomfortable for Harold Wilson during much of the Vietnam War.

Many of his current would-be tormentors on the Campaign Group left ("would-be" because Blair is less tormented by such shouts and murmurs than any previous Labour leader, Harold Wilson very much included) would not like the fact that such an option would indeed be what I called on Tuesday a sort of third way. Withholding British combat troops would almost certainly not stop a dangerous and, outside America, deeply unpopular US war being launched before the inspection process had been completed to the satisfaction of – say – Hans Blix. And if it didn't, Mr Blair would presumably see to it that the US got from Britain all the help that he could legally provide, including the use of bases and the securing of Iraqi borders.

Any move along the lines floated by Mr Rumsfeld would be Wilson-plus in a big way. And of course, as the US Defence Secretary suggested on Tuesday night, British troops would play the kind of peacekeeping role that even the Campaign Group recognises they are extremely good at. Neither would the Bush administration like it, blissfully oblivious of how far its own swaggering lack of interest in multilateralist diplomacy since the inauguration would have contributed to the failure, if there is one, of a UN resolution this week.

But this might be slight compared with the consequences, not just for Mr Blair but quite possibly for Britain's future reputation and interests in the Middle East, of following the US into a globally destabilising unilateralist adventure.

For a start, those who assume that Mr Blair will be fatally weakened because he has refused to rule out action unsanctioned by the UN for so long are missing something. Not ruling out action without a second resolution – Mr Blair's stance from the start – was arguably the right tactical judgement because it was the best way of screwing down Saddam. But it is not the same as ruling it in, which even yesterday Blair did not explicitly do. And as for complaints from the left about the use of bases, well Britain would hardly be acting differently, in qualitative terms, from supposedly pacifist Germany.

Now all this may prove irrelevant if there is a second resolution, about which Mr Blair sounds rather confident. And if there is one, it will be a genuine triumph for British diplomacy and for Mr Blair's brokering of a compromise around the draft ultimatum to Saddam. Maybe, too, Mr Rumsfeld got it wrong on Tuesday night, or was staging an elaborate stunt to flush out Mr Blair in case he was, as the Washington hawks would see it, wobbling. Maybe he was on to something. Mr Blair was still shoulder to shoulder with George Bush yesterday, and he may well remain so whatever happens. Nevertheless, if the resolution does fail, life after New York is another country.

d.macintyre@independent.co.uk