Stand behind the troops, don't hide behind them

Why is it that any criticism of the Bush administration's execution of the war in Iraq equate to a denigration of the troops? Our troops are adults. They can take criticism and if they screw up they deserve it (didn't one of them get 10 years jail time for torture recently-- does that mean we aren't supporting our troops? I don't think so. Others may disagree). Conversely the president doesn't seem to be able to take criticism. That doesn't change the fact that if he has screwed up he deserves it.