The Next Step? Think Vietnam.

If you want to understand the futility of america's current situation in Iraq, last week provided a vivid microcosm. On Thursday, just hours before a series of car bombs killed more than 200 people in the Shia stronghold of Sadr City, Sunni militants attacked the Ministry of Health, which is run by one of Moqtada al-Sadr's followers. Within a couple of hours, American units arrived at the scene and chased off the attackers. The next day, Sadr's men began reprisals against Sunnis, firing RPGs at several mosques. When U.S. forces tried to stop the carnage and restore order, goons from Sadr's Mahdi Army began firing on American helicopters. In other words, one day the U.S. Army was defending Sadr's militia and, the next day, was attacked by it. We're in the middle of a civil war and are being shot at by both sides.

There can be no more doubt that Iraq is in a civil war, in which leaders of both its main communities, Sunnis and Shiites, are fomenting violence. The assault on Sadr's Ministry of Health was likely retaliation for a recent mass kidnapping at the Ministry of Education, which still retains some Sunnis. The Ministry of the Interior houses the deadliest killers from the Badr Brigades, the other large Shiite militia. Badr's Bayan Jabr built the death squads when he ran the ministry; he's now Iraq's Finance minister, in charge of its resources. This is the Iraqi government we are protecting, funding and attempting to strengthen. To speak, as the White House deputy press secretary did last week, of "terrorists ... targeting innocents in a brazen effort to topple a democratically elected government" totally misses the reality of Iraq today. Who are the terrorists and who are the innocents? Among the most pro-American voices to emerge from the new Iraq have been two young Baghdadis, Omar and Mohammed Fadhlil, whose three-year-old blog, Iraq the Model, has promoted a relentlessly upbeat and hopeful message. Last week they threw in the towel. "I believe that America would like to see Iraq emerge as a model for the region," Mohammed wrote. "But that cannot be done without having a cooperative Iraqi partner on the ground who shares similar views for Iraq and the Middle East. And that's the point--that partner does not exist, at least not in the government."

The American Army has more than enough troops to confront the Mahdi Army. The problem is political, not military. U.S. forces have been repeatedly blocked from going after Mahdi leaders. This month they were forced by the Iraqi government to abandon raids into Sadr City in search of a kidnapped American soldier. They were not even allowed to stop traffic in the neighborhood. Will more troops change that?

To the contrary, both sides now see American troops as the problem. The Shiite ruling coalition and the Sunni insurgency both believe that if only the United States were to get out of the way, they could defeat their enemies outright. That's why, in the most recent poll of Iraqis, taken in September, 91 percent of Sunnis and 74 percent of Shiites said they wanted American forces to leave within a year.

While these are not conditions that suggest a political deal is likely, there is nothing to be lost in trying. When President Bush meets with Prime Minister Nuri al-Maliki in Jordan this week, he should make clear that Iraq's leaders need to come to an agreement that meets both sides' key demands on such issues as autonomy, oil revenues and amnesty. But he needs to deliver an ultimatum: either the government begins implementing such a deal by January or American troops will begin a drawdown, leaving the core tasks of security to Iraqi forces.

There is much moaning in Washington about the return of the "realists," like James Baker, who are allegedly pushing to surrender America's ideals as the price of bringing stability to the situation in Iraq. In fact, even stability in Iraq is unattainable. What we will soon need is a supreme act of realism, dictated not by the ascendancy of a school of thought in Washington but by events on the ground in Iraq. We will need a Kissingerian effort to extricate the United States from the catastrophe that Iraq has become.

Iraq is not Vietnam. But America's predicament in Iraq is becoming increasingly similar to the one it faced in Southeast Asia more than 30 years ago. Henry Kissinger's negotiations to end the Vietnam War have been criticized from both the left and right. One side thought he moved too slowly to get us out, the other that he gave up too much. But looking at our circumstances in Iraq should give us some appreciation for the difficulty of his task. With a losing hand and deteriorating conditions on the ground, Kissinger maneuvered to extricate the United States from a situation in which it could not achieve its objectives, while at the same time limiting the damage, shoring up regional allies and maintaining some measure of American credibility. A version of such a strategy is the only one that has any chance of success in Iraq today.