NOT LONG AGO RICHARD COHEN of the Washington Post wrote a column about Iraq headlined "As in Vietnam, dereliction of duty all over again." The Vietnam analogy has been part of the Iraq war story since the fighting started (in fact, since before it started). The Bush administration often deals with its critics by ignoring them. This time it can't. Too much rides on the president looking these critics in the eye and telling them: Damned right this is Vietnam all over again. Only this time we will not get scared and walk out in the middle. This time we will stand fast, and repair a piece of the American psyche that has been damaged and hurting ever since we ran from Vietnam in disgrace way back in April 1975.

Of course any citizen is welcome to criticize the conduct of any war--tactfully, without giving aid and comfort to the enemy. Maybe we are doing things all wrong in Iraq. But those who launch the Vietnam analogy at the administration are lobbing heavy artillery for a different reason. They are predicting (with obnoxious schadenfreude) that Iraq will turn out like Vietnam in the end: We will proclaim ourselves beaten, give up, and go home. The sooner we understand this, the sooner we will do the intelligent and humane thing and surrender.

These critics ought to be told firmly that Iraq is indeed another Vietnam. Once again we are in the middle of cleaning out one of the world's ugliest abscesses, which turns out

In Iraq as in Vietnam, the government gave the American people an unrealistic estimate of how hard the war would be. Both times it was an honest but costly mistake, which could probably have been avoided.

In Iraq as in Vietnam, it's impossible to say whether our intervention was justified by self-interest. (Churchill: "It is not given to the cleverest and most calculating of mortals to know with certainty what is their interest. Yet it is given to quite a lot of simple folk to know every day what is their duty.") In Iraq as in Vietnam, we have promised to rescue a suffering people from its tormentors. (Our duty was not to plant democracy in Iraq; our duty was to put an end to unbearable suffering. But planting democracy seemed like the only way to accomplish this goal, unless we were bucking for a new colony.) In Iraq as in Vietnam, the fighting is ugly and bloody. But in Iraq, unlike Vietnam, we will stay until we are finished.

Not many nations get a second chance to show the world and themselves that they are serious after all, that their friends can trust them and their enemies ought to fear them. There is no way we can atone for the blood and death we inflicted (indirectly) on South Vietnam by abandoning it to Communist tyranny. That failure can never be put right. But we can make clear that "No More Vietnams" is a Republican slogan. It means that we will never again go back on our word and betray our friends, our soldiers, and ourselves.