Colin Powell said, "if you break it, you own it."
That's exactly what's going on in Iraq.
I'm afraid retreat is NOT an option in Iraq. The Spainards can retreat like a homeless dog but that's not possible for the United States. The world can't afford to let the Americans leave Iraq immediately, whether they like it or not. It will be much worse and the remedy can be worse than the "sickness".
Some may see similarities to Vietnam but I see this as another Lebanon.
United States must stay in Iraq, regardless of who's in charge in 2005, because,
a) The safety of the oil supply is precarious, especially nowadays we have China to fight for the same resource. In the meantime the Americans aren't willing to sacriface their SUVs and high consumption of oil lifestyle yet. I am not even talking about any possible coup and "decapitation" attempt to the Saudi Royal family in Saudi Arabia, possibly instigated by Islamists.
b) Any retreat from the Islamic world can be seen as a "defeat" to the war of the wills. The Islamic militants will be bolden and encouraged to murder people all around the world as they see fit.
How could the most powerful country in the world tolerate himself to be blackmailed by a bunch of thugs?
Obvious the Americans don't have the stomach and the will to exterminate the massive number of thugs with deadly arsenals at the disposal.