The war in Iraq is unwinnable. It is becoming increasingly clear that the United States cannot obtain decisive victory in any conflict that lasts longer than a few weeks or months. Since World War II, we have lost or been stalemated in Korea and Vietnam, and Iraq appears to be headed in the same direction and for the same reason. Politicians don't have the will to support a protracted war because Americans have no stomach for it.

Wars require sacrifice, and we have become a nation unaccustomed to adversity. Our leaders have asked most of us to give up precious little to support the war effort. Except for those whose family members are serving in the military, an ever smaller fraction of the population, we go about our daily lives no differently than we would if we were at peace.

Gen. David Petraeus testified before a dubious and hostile Congress this week. Democrats all but accused the four-star general of lying to them when he reported that conditions in Iraq have improved since the U.S. committed more troops and changed its mission to hunt down insurgents and secure and hold neighborhoods. And even some Republicans seemed more interested in obtaining a promise that the president will begin to withdraw American troops quickly than they are in winning the war.

It would be easy to blame the politicians for their lack of will. But elected leaders generally reflect the views of the electorate. So why is it we've given up this fight? There's plenty of blame to go around.

The administration has badly bungled the war, first by committing fewer troops than were needed to provide security once we toppled Saddam, then by changing its rationale for the war. Democracy in Iraq is a worthy goal, but one that few Americans would have committed the nation to war in order to obtain even if the Iraqis were capable of non-sectarian self-government, which they have yet to demonstrate.

But the Democrats share responsibility as well. They have consistently put politics before the national interest. Their rhetoric has given aid and comfort to the enemy. They seem more interested in blaming President Bush than in securing victory. And they can't even make up their minds whether they want to end the war now or simply hamper the military's ability to fight it effectively.

In the end, however, if we lose this war, Americans themselves will be to blame. We're more focused on Britney Spears and Paris Hilton than we are on fighting terrorism. Six years after the horrific attacks on American soil, we've largely forgotten what we're up against. Except for minor inconveniences at airport check-ins, most Americans are not asked to share any burden to win this war.

During World War II, our parents and grandparents made enormous sacrifices to ensure victory. They went without basic necessities, not to mention luxuries, so that our troops would be properly fed and clothed. They invested their savings in war bonds. Americans of all classes enlisted even before they could be drafted. Women entered the workforce so that men could fight. Newspapers put the nation's security first, never using the First Amendment as an excuse to reveal information that could jeopardize the war effort. Our partisan differences, no less dramatic than they are today, ended at the water's edge.

Our losses in Korea and Vietnam did not ultimately jeopardize American security. But a loss in Iraq will have far greater consequences. Iran, which is on the verge of becoming a nuclear power, will be emboldened by our failure to win against a relatively small but ruthless enemy in Iraq. At the very least, we can expect a protracted and perilous new Cold War against a less rational enemy than we faced in the Soviet Union.

It is difficult to see how we might turn this around, surely not unless Americans wake up to the danger.