Blame the People!
Was just watching "This Week at War," on CNN and a general (sorry, didn't catch the name) argued against a non-binding Senate resolution against a troop surge by saying that it undermines our military's confidence in its mission. Then, the general invoked Viet Nam saying that he didn't want a repeat of a situation where the American people would turn against a war and abandon its soldiers.
This kind of argument is going to get more and more common -- war supporters will claim that war opponents should just shut up because they're abandoning the troops, as if the war opponents should have no voice in policy.
They will also imply that the people were all for the war at first but now don't have the stomach to see it through.
Just remember, there was never a broad based public clamor for invading Iraq. Nor was there ever a clamor for getting involved in Viet Nam. Both wars were started by presidents with their own agendas. The worst you can say about the people is that they didn't rabidly oppose the invasions before they happened. But it's not like you can say that the American people wanted to invade Iraq until it went bad. The people were divided about invading it and, when it went bad, the scales tipped against it. The troops are not being abandoned by anyone. Support for invading Iraq was always tenuous at best. Now, mainstream opinion is against continuing the fight.
The troops are supposed to be an extension of the will of the American people. That will says to bring them home.