Just to add a dose of reality, most estimates say that it will take at least two years to withdraw from Iraq, without retaining any kind of ongoing role in whatever you choose to call the debacle.   Just for example, if all 160,000 troops lined up at the Baghdad Airport, they would fill something like 500 airliners. That would be quite a car bomb target! This does not consider the fact that a very large proportion of the equipment owned by the US military is currently in Iraq and it must be relocated back to the States. It took much longer than that to withdraw from Vietnam, and we dumped much of our equipment into the South China Sea.

Of course, starting sometime soon would be a good idea...