What is Robert Gates really upset about?

Robert Gates was kept on from the Bush administration in an effort at bipartisanship

The biggest revelation in former Defence Secretary Robert Gates' memoirs is the former Pentagon chief, a man know for his calm and charm, seethed with an inner fury at the Washington game.

His criticisms carry huge weight - he's served eight presidents, so he knows what he is talking about.

When he accuses the Obama administration of playing domestic politics with foreign affairs, micromanaging operations and allowing junior staff to treat the military with disdain, it is not the complaint of some naive junior officer who's just wafted into headquarters from the frontline.

Mr Gates' most serious charge is that President Obama lost faith in his own Afghanistan policy, and did not believe it would succeed - his overriding objective was simply to get out.

I've little doubt he's absolutely correct, but he pulls his punches - and that is frustrating because he is in a position to make judgments that the rest of us cannot, for lack of all the facts.

Critical is when exactly Mr Obama lost faith - was his policy cynical, or did it simply not go as he hoped?

You can argue that Mr Obama was guilty of a tremendous moral failure - that he sent men and women to die as political cover for a policy that had little chance of success.

You can argue that he was too quick to withdraw and needed to give his own policy more time - whatever his political promises.

You could also argue the president got it right - a new untested president had to give a military solution one final chance, but had to avoid getting sucked into an endless commitment to carry on a war the American people wanted to end.

Yet Mr Gates doesn't come down on one side or the other, although he hints Mr Obama made the correct decisions.

So in the end his criticisms are about belief and tone, about Mr Obama's lack of enthusiasm for the war, and lack of trust in the military, rather than faulty policy.

Perhaps that is the sort of sophisticated, bipartisan, relaxed judgment that one might expected from Robert Gates - however angry he is inside.