I've said this many times in the past but it is always important to keep in mind, especially as more and more bad news comes out of Iraq, that the situation there has never been politically settled.  Yes, there was a truce of sorts, a lull in the violence, but that simply reflected tactical decisions by various Iraqi militias and political actors to bide their time until the US pulled out.  Politics in Iraq is not, and has not been since the US invasion, self-sustaining.  That is, the relative calm of recent months has been predicated upon US power, not fundamental reconciliation among competing political forces within the country. 

Bush thus left Obama with an impossible situation: remain in Iraq indefinitely, which most Americans do not want (and which would, as it has now, eventually spark more attacks on Americans) or create a time frame for pullout which would, as it has, gradually reveal the lack of political settlement in the country. 

There is no good way forward because….

Bush lost the war.