Donald Macintyre: What will Mr Blair do if the US extends the war to Iraq?

'The Tories could find advantage if the PM decided he could not support Bush in Iraq'

As the representatives of their closest neighbours and the further-flung big powers hover around the 28 Afghan delegates in Bonn trying to reconstruct a failed state, Rudyard Kipling meets John le Carre. The Great Game played out in A Small Town in Germany. It would be an intriguing, almost entertaining, prospect, if it were not for the background of distant slaughter and bloodshed against which the talks have been taking place.

Or if it were not for the fact that the stakes are so high. If nothing else, the ruthless suppression of the prisoners' uprising in Mazar-i-Sharif, is a reminder of how the Allies cannot judge war in Afghanistan a political as well as a military success unless stable government can at last be installed. And the encouraging first signs are that it may be. Mr Blair knows this better than most – which is why he appears to have been so keen to persuade the United States a fortnight ago of the virtue of sending a sizeable force to Afghanistan for stabilisation and humanitarian purposes.

But if there were differences – their exact nature still enveloped in diplomatic fog – over this, they could yet be trifling compared with the fall-out from what the US decides to do next, especially about Iraq.

It's fashionable to dismiss anything the Tories do as irrelevant. This shouldn't be applied to Iain Duncan Smith's decision, disclosed on the eve of a visit to Washington which began last night, to support the extension of war to Iraq. The degree to which Tony Blair has forged bonds with President George Bush is one of the most significant of his diplomatic achievements in 2001. But there are still hawkish corners of Washington where there is right-wing irritation at what is quite widely seen as his restraining role, closer to Colin Powell than – say – Paul Wolfowitz. In such quarters, Mr Duncan Smith will no doubt be made welcome.

But that isn't the real significance of Mr Duncan Smith's new positioning. It owes much more to his perception, that this is how, in the end, the Americans will jump. And here the Tories could punch above their woefully limited parliamentary weight, if only by underlining the dilemma Mr Blair would face if Mr Duncan Smith's expectation proves right. The Prime Minister's wholehearted – and wholly vindicated – support of the US operation in Afghanistan left no space for the Tories to appear more determined in the war against terrorism than he is.

Indulging the luxury of opposition, in which they are faced by none of the painful life and death decisions Mr Blair has to take, they could seek so to project themselves if the Prime Minister decided he could not support a full US military operation in Iraq. If he did not so decide, he could be damned by many in his own party. If he did, he could be threatened with the taunts of a bellicose opposition and their Fleet Street cheerleaders.

The international dilemma is much greater. What will – rightly – weigh much more heavily with Mr Blair than the posturing of an opposition heroic in safety, will be the relationship with the US. He can exert pressure, but, as he well knows, he cannot in the end stop a US war on Iraq, if there is to be one. He knows that the coalition would almost certainly fall apart, not only in the Muslim world, but in much of Western Europe – notably France.

The question of whether he forfeits his place as the US administration's most valued ally, or influence in Europe and quite possibly much further afield, becomes a much sharper one. In such circumstances, in the words of one of his colleagues, it would be "very difficult" to back the US, "very hard" not to.

At present, the British position, firmly restated by the Foreign Office minister, Ben Bradshaw, on Tuesday, is that the UK is against action against an enemy not demonstrated to have been connected with the events of 11 September. This was the reassuring message which Jack Straw took at the end of last week to Iran, which for all its long history of enmity with Iraq, is deeply concerned about the prospect of an extension of war in the region.

On the one hand, it's entirely possible that this stance will not, in the end, be tested to destruction. One British Cabinet minister suggested this week that the prospect of the dilemma even arising had a probability of only about 15 per cent. Those who have travelled with Mr Blair to Washington have, from the first, detected little sign that the President was anything but wary of war in Iraq. General Powell recently told The New York Times: "I never saw a plan that was going to take [Saddam] out. It was just some ideas coming from various quarters about let's go bomb."

Given the – no doubt correct – implication that bombing cannot be relied on to topple Saddam, it follows that some form of US ground force might have to be mobilised to do the job – something which even Pentagon planners might baulk at. On Monday, Mr Bush reiterated the demand on Saddam Hussein to let weapons inspectors back – which has the sanction of a UN resolution and which the British and Europeans therefore support – or "face the consequences". But his answer to the question of what that means – "He'll find out" – suggests that he may not yet have made up his mind.

On the other hand, there are ominous signs emerging from the US. Leaving aside the possibility that fresh evidence, whether conclusive or not, could yet be produced linking Iraq to 11 September (or old reports about contacts between a bin Laden associate with Iraqi intelligence in Prague is elevated to a greater status than it can bear at present), another argument has begun to take shape among US hawks. Since the Iraqi regime is building weapons of mass destruction, and is known to consort with terrorists, and since Osama bin Laden made clear his desire to acquire such weapons, the US is entitled to take action against Iraq.

Furthermore, Russia, with an eye to its own commercial interests, is not yet ready to agree with the Western allied effort to redraw the sanctions list to be tougher on exports which could be related to weapons of mass destruction, and more generous on those with a proven humanitarian purpose. Although Russia is likely to disclose in New York today that it will agree to this in another six months, this temporary deadlock could also be used by the Washington hawks to strengthen the case for military action.

For now, the outcome remains unclear. It's just possible that Mr Blair could yet seek to justify support for extending the war to Iraq – which all the signs are he does not want – if it was coupled with a serious US Middle East initiative in which the US finally applied irresistible pressure on Ariel Sharon to agree land and a state for the Palestinians in return for peace and Israeli security. But what guarantee is there that the US is yet ready for that?

Mr Blair may yet be able to overcome all these problems as he so signally did, confounding his critics, over Afghanistan. But he too is at the mercy of deliberations in Washington. Through no fault of his own he could yet be between a rock and hard place.

d.macintyre@independent.com