I said in an earlier post that one who protests the United States' continued presence cannot, even if right, do so without doing harm. I do not mean to say that those protesters are wrong (although I am ignorant of what the proper course of the US should be now that it has invaded Iraq).
I am saying that because Mr. Bush ordered the invasion (and because some supported him, and others, like me, did not speak out against his plans to invade in the first place), we face a situation where nobody is clean. Any decision--silence, apathy, advocacy for withdrawal, advocacy for a "troop surge"--is tainted by the collective guilt we share by virtue of the situation. There may be a right decision on what the US should do, but that decision will not come without costs. The loss will be real. Some people, like Too Clever By Half, claim that whatever the cost, it's better to withdraw now. Still, even he acknowledges what he says is the probable outcome for Iraqis.
Finally, might I say that the question of blame doesn't enter into consideration? One may, quite rightly, blame Mr. Bush for the war. One might blame Mr. Hussein. One might blame me. Still, now that the invasion has occurred, we share the guilt (even if not the blame).