A great deal of the credibility of the Petraeus report is based upon the idea that since he’s a general, he is therefore respectable and we can trust us to give it to us straight.

The problem, of course, is that by this time, any high-level Iraq War posting is more likely than usual to attract a general who is more oriented towards political ambition than would be otherwise. The good generals have resigned over this in principle. Among what we have left are the kind of people who gravitate to the top in an administration like this one.

Evidence of the fact: Petraeus, it seems, has presidential ambitions.

The US commander in Iraq, General David Petraeus, expressed long-term interest in running for the US presidency when he was stationed in Baghdad, according to a senior Iraqi official who knew him at that time.

Sabah Khadim, then a senior adviser at Iraq’s Interior Ministry, says General Petraeus discussed with him his ambition when the general was head of training and recruitment of the Iraqi army in 2004-05.

“I asked him if he was planning to run in 2008 and he said, ‘No, that would be too soon’,” Mr Khadim, who now lives in London, said.

General Petraeus has a reputation in the US Army for being a man of great ambition. If he succeeds in reversing America’s apparent failure in Iraq, he would be a natural candidate for the White House in the presidential election in 2012.

Which means that Petraeus is a political animal as much as, if not more than, a clean-cut military man, and what he does now is very likely colored by what he believes will serve him in a political campaign not too far in the future.

I know what the knee-jerk right-wing response will be: what about Wesley Clark? Well, his service in the military gives him the same basic standing as Petraeus. Because we know Clark has presidential ambitions, we weigh his words with those ambitions in mind. The exact same applies to Petraeus. Both generals must be considered not to simply give the straight story, but rather the story that serves them best as far as a political campaign is concerned.

The difference is, Petraeus is active, still serving in the military, and so should be above such things. That is precisely the image the White House is depending on: this report comes not from a politician, but from a general, and we can trust them.

Petraeus, as it turns out, however, is just another politician. And his performance in spinning the data to political advantage certainly gives us no reason to doubt this.