Washington ? If you think there is an echo in the air when officials discuss the twin crises in Iraq and Lebanon, you are not hearing things. In both cases, the argument for carrying on the destructive current policy comes down to a claim that “we can’t afford to let the other guy win.”

President Bush says over and over that cutting short the occupation of Iraq would turn that country over to the terrorists and embolden them to carry their wicked plots ever closer to our shores. He also endorses – implicitly – Israeli Prime Minister Ehud Olmert’s view that an early cease-fire with Lebanon would strengthen Hezbollah and make its prime sponsor, Iran, even more of a threat to its neighbors. That political support enables Olmert to wage the kind of campaign he has in Lebanon.

In both cases, the argument is not that continuing on the present course will necessarily or likely yield a positive result. On the contrary, it is basically a claim that it is unacceptable to change – because the other side will claim a victory.

But if Hezbollah in Lebanon and the insurgents in Iraq really are deadly threats to Israel and the United States, respectively, then those nations should have used their full military might – which is overwhelming – to deal with the menace.

For Israel, that would have meant a large-scale ground and air offensive aimed at driving the Hezbollah forces far from the border and eliminating their missile sites. But Olmert stopped short of making the full commitment to eliminating the enemy, instead waging an effort largely from the air, using U.S.-supplied munitions, that is wreaking havoc on the civilian population of Lebanon.

For the United States, it would have meant moving into Iraq with a large enough force to control the country after Saddam Hussein was toppled, not the pared-down deployment that Defense Secretary Don Rumsfeld insisted would be adequate. And, as Tom Ricks of The Washington Post describes in deadly detail in his book “Fiasco,” it would have meant serious planning for the occupation. That planning never took place, making it impossible for Iraqis to live their lives with hope.

In both cases, the leaders of government failed to make the kind of commitment that could have produced a lasting victory.

Now, they are reduced to saying that they cannot accept defeat. That is a terrible turn.

But once the hope for victory is gone, the issue remains: What do you do? The answer from Bush and from Olmert is: Carry on. Do not waver. And do not question the logic of prolonging the agony.

History suggests that is not always the right answer. The United States has failed to achieve victory in two of its recent wars – with very different results.

In Korea, we settled for a stalemate, a line dividing North and South Korea, after Gen. Douglas MacArthur’s rush northward brought the Chinese into the fight and led to a terrifying retreat by the American forces. No one would claim that has been an ideal solution. North Korea remains a communist dictatorship, and its nuclear ambitions and missile development are a continuing problem for the United States and the Asian neighbors.

On the other hand, North Korea has not moved against South Korea for more than 50 years; the peace has held.

The other war was in Vietnam. (I know there are still people who believe it was lost in Washington, on Capitol Hill, when it could have been won in the jungles. But the fact is that we withdrew, and Saigon fell.)

It is hard to remember now, but at the time, we were told that if Ho Chi Minh prevailed, communism would roll south through Malaysia and spread to the Philippines and threaten Australia – to say nothing of American influence in the Pacific. We took those warnings seriously, and so it was a bitter moment when the Viet Cong occupied the old American embassy in Saigon.

And today, the embassy is again open – in Hanoi – and the United States is trading freely with a united Vietnam.

The point is that history and economics have their own logic. A military mission that fails to yield a victory does not always presage disaster. Today, virtually no one argues that we should have continued fighting the North Koreans or the Viet Cong and North Vietnamese.

Can we think about the costs of carrying on, without an end in sight, against Hezbollah and the insurgents in Iraq?