Part of Andrew's quote of the day is Harvey Mansfield's assertion "that if America is an empire, it is the first empire that always wants an exit strategy."
I don't think that's really true. I've been reading Robert Meredith's book on The Fate of Africa lately, and one striking thing about the section on decolonization from the mid-1940s to the mid-1960s was precisely the extent to which in many circumstances the imperial powers were looking for an exit strategy. Outside of the unusual case of Algeria, it was almost never the stated policy of England or France (Portugal was different) that they wanted to stay forever. Instead, as with the US in Iraq, there was always just a reason you couldn't leave right now, and then another reason, and some more problems, etc., etc., etc.