The destruction of Balad, a mixed-but-mostly-Shiite-city in a Sunni-dominated province, is excellently recounted by Ellen Knickmeyer of The Washington Post. About a year and a half ago, I was at a barbeque with a prominent Iraq-war enthusiast, and in the process of explaining to me why I was wrong to advocate withdrawal, he mentioned that Iraqis' high rates of sectarian intermarriage would be a strong bulwark against civil war. Well, goodbye to all that.

Several things stand out here, but let's focus on the most important. The U.S. learns about the sectarian rampage a day after Sunni death-squadders murder 17 Shiites. Balad, it should be said, is the site of a huge and probably permanent U.S. military base. The U.S. puts together what Knickmeyer calls a "quick-reaction" platoon to respond to what's now a mass killing. But the Shiite officials in Balad say, essentially, hang back and let us finish what we started here.

Remember this every time you hear that U.S. troops are the only thing standing between Iraq and total sectarian chaos. The Shiites in Balad say let us finish this and the U.S. says yessir. Maybe a different account will emerge in the coming days, but consider this to be the wages of pretending that Iraq has a "national unity" government instead of competing centers of sectarian power: when the "Iraqi officials" say stop the U.S., under pains of inconsistency, must stop, even when that means the revenge killings will go unrestrained. This is the necessary consequence of the fiction that Iraq is a sovereign country; the fiction that Iraqi forces are standing up; and the fiction that Iraq's rulers are more interested in stopping the sectarian violence than in instigating it.

The obvious objection to this point: Well, Ackerman, are you saying the U.S. should have defied the orders of the Balad officials and reinvaded the town? No, I'm saying U.S. troops should get the hell out lest they be drawn into that nightmare, and no amount of force will represent a prophylactic to such a nightmare when the will to fight among Iraqis is there, particularly among the leaders that the U.S. believes it needs to answer to in order to avoid the charge of imperialism. And speaking of willpower, consider the will of the U.S. commander here: he dispatched a "platoon-sized quick-reaction force. " A platoon! For a city of thousands! Clearly, the U.S. Army and MNF-I does not want to get drawn in to their civil war. I sang a different tune for the Balkans, but the Balkans was a different situation. Here, let's give the Army what it wants.

A final thought, courtesy of Hussein Abid Ali, who ran a falafel shop in Balad. You can tell he's a Shiite from his name.

Balad's Shiites had been living alongside Sunnis for hundreds of years, Ali said, staring bleakly at the road outside. He had a Sunni son-in-law and Sunni friends, he said. It took the American occupation, he said, to change all that.

"What do you want to know?" Ali demanded bitterly. "How we reached this level? How we started to kill people according to their identity? How this sectarian strife was brought to us?"