Steyn, as he so often is, is right on the money.
Iraq is not Vietnam. But if we want to be realistic about it, Vietnam was not "Vietnam". "Vietnam" has become the all purpose leftist bugbear of a intractable quagmire that is unwinnable. This was not true of Vietnam at the time and it is doubly not true about Iraq today.
The one parallel between Vietnam and Iraq is that if we pull out before achieving victory, the region will degenerate into internercine genocide which defies the imagination.
In Cambodia the Khymer Rouge executed everyone who wore glasses, on the suspicion that they were part of the literate elite. If we withdraw prematurely in Iraq, the coming bloodbath will make us long for such days.