The US request for British troop cover is curious. Curious that the US allows itself to be in the position of asking.
Rumsfeld: To the extent they're not [able to participate], there are workarounds and they would not be involved, at least in that phase of it. (March 11, 2003)This is an administration which doesn't really give too much of a damn about having allies or not, yet to have to ask for this troop movement surely exposes the kind of military and political weakness that can't be easy for the neo-cons to display.
The motive is pretty unlikely, I'd say, to be political. Any gain in having the UK as an ally in Iraq is already well known to the US electorate. The risks of political damage by allowing the UK to say "No" thus exposing rifts outweigh any potential advantage. If then the motive is military the UK should have absolutely no question about providing forces assuming our military people are happy with arrangements. If 650 of our troops can make a positive difference to the operations up north in Iraq then that opportunity should be seized.