John Rentoul: A civilian took us to war in Iraq. And it may take an honest soldier to get us out again

Tony Blair has a problem with Iraq. Professor Brian Brivati, contemporary historian and Labour biographer, is possibly the only intellectual in the country who has become more impressed with the Prime Minister because of his foreign policy. "The years since 2001 have radicalised me, but in the opposite direction to most people I know," Brivati wrote in the New Statesman on the fifth anniversary of 9/11, predicting that history would judge Blair's "cause of humanitarian intervention" kindly.

Last week the professor must have felt lonelier than ever. The Lancet estimated the violent death toll since the invasion of Iraq at 600,000. Then General Sir Richard Dannatt, head of the British army, said "history will judge" whether the hope of creating a "liberal democracy that was an exemplar for the region" was "naive", but "I don't think we are going to do that. I think we should aim for a lower ambition" - namely to "get ourselves out some time soon".

Blair once wearily described himself as "beyond anger" when his motives in Iraq were questioned, but I suspect that he briefly re-entered that emotional zone when news of Sir Richard's interview reached him during the Northern Ireland talks in St Andrews. Especially because he must have realised immediately that, in his weakened final months, he could hardly sack Sir Richard for saying what the squaddies want to hear.

However, Blair does not have as pressing a problem with Iraq as does Gordon Brown. For some months, an air of resignation has been detectable in the Prime Minister's attitude to Iraq. He knows it is out of his hands; there is little more he can do but wait for the verdict of history. But if it is Brown who takes over in No 10 next year, he will have to decide between two competing strategies. One is to declare the job done and pull the British forces out; the other is to cut the numbers from the present 7,000 but to keep a substantial force in Iraq for many years.

Brown wants to be different but does not want to be accused of cutting and running. Even if everyone supports cutting and running, it might not look pretty when it happens. There is a danger that he might look weak after the "strong" Blair, even if most people say they have had enough of that kind of "strength". Brown has told his inner court that he intends to "out-Blair Blair" when he takes over, and he did say in a speech last week: "I do not think that in government New Labour has yet been New Labour enough." He was not talking about foreign affairs, but you get the drift.

It is possible, then, that Sir Richard wanted either to put pressure on Brown, or to make it easier for him, to ditch Iraq for Afghanistan. As the general said: "There is a clear distinction between our status and position in Iraq and in Afghanistan, which is why I have much more optimism that we can get it right in Afghanistan."

That is where Sir Richard's interview carried its explosive power. The implication that the mission in Iraq is less legitimate than that in Afghanistan was reported as if it were a truth bomb. The antiwar media monomania is interested in only one question: when are the warmongers going to admit they got it wrong? Pulling the troops out because they are making matters worse rather than better has been defined in advance as an admission of error.

This argument has turned endlessly through the same cycle ever since the statue of Saddam was toppled three and a half years ago. Foreign troops out, say voices both in Iraq and at home. But that might make matters worse for the Iraqis, suggests a more tentative second thought. Well, troops out soon then, everyone agrees.

Hence, too, the treatment of the new Lancet research. No one can dismiss it lightly, but neither has anyone yet explained why a larger survey with a different methodology suggested that there had been 24,000 "war-related deaths" in the year after the invasion, as against 98,000 in the first Lancet study two years ago. The Iraq Living Conditions Survey, carried out for the UN Development Programme, simply did not fit the media template. Nor do findings of other surveys that find that most Iraqis (77 per cent in the case of an opinion poll in February this year) say that, despite all the hardships suffered, getting rid of Saddam has been "worth it".

To that extent, Sir Richard's expressions of surprise that anyone found his conversation with the Daily Mail "newsworthy" might be justified. What he said about pulling out "soon" could be glossed flexibly as "we're going to see this through". And it is a statement of the obvious - albeit one that Blair would rather not have made - that coalition troops attract trouble as well as suppress it. But he crossed a line by suggesting that the objective of spreading democracy had been naive, and by saying that the US and Britain had "kicked the door down" to invade Iraq uninvited. Those were the parts of his Mail interview that Blair conspicuously did not endorse on Friday. Nor was it helpful of Sir Richard to say that the presence of British troops in Iraq exacerbate our difficulties "around the world". The problem is that the presence in Iraq is used by Islamists to promote the lie that Britain and the US are engaged in a war against Muslims.

Sir Richard was safe in saying what soldiers know perfectly well. His presentation of himself as a truth-teller must be irritating to politicians, but he did not get to be head of the British army by being an innocent. He is a politician too, of a different kind, and spoke of the British army as his "constituency". It helps with the politics of defence if you have the support of the squaddies. And judging by the adulatory response from service personnel on the internet, his Daily Mail and follow-up interviews went down well.

Now, not only can Blair not sack him, but Brown cannot either. Sir Richard wants two things from the Government. He wants money and resources, which he has got, and he wants to get most of the Army out of Iraq, the timetable for which he brought significantly forward last week.

What he did was nakedly political and even, as some have spluttered, unconstitutional. But if democratic politics is about the mobilising of public opinion, who will bring him to book? When the history of Britain's involvement in Iraq in the 21st century comes to be written, it may well be recorded that it was Tony Blair that got us into it, and General Sir Richard Dannatt who got us out.