BAGHDAD, Iraq – While American politicians and generals in Washington debate the possibility of civil war in Iraq, U.S. officers and enlisted men who patrol Baghdad daily say it has already begun.

Army troops in and around Baghdad interviewed in the last week cite a long list of evidence that the center of the nation is coming undone: Villages have been abandoned by Sunni and Shiite Muslims; Sunni insurgents have killed thousands of Shiites in car bombings and assassinations; Shiite militia death squads have tortured and killed hundreds, if not thousands, of Sunnis; and when night falls, neighborhoods become open battlegrounds.

“There’s one street that’s the dividing line. They shoot mortars across the line and abduct people back and forth,” said 1st Lt. Brian Johnson, a 4th Infantry Division platoon leader from Houston, describing the nightly battleground that pits Sunni gunmen from the Ghazaliyah neighborhood against Shiite gunmen from the Shula district.

As he spoke, the sights and sounds of battle grew: first, the rat-a-tat-tat of fire from AK-47 assault rifles, then the heavier bursts of PKC machine guns, and finally the booms of mortar rounds crisscrossing the night sky and crashing down onto houses and roads.

The bodies of captured Sunni and Shiite fighters will turn up in the morning, dropped in canals and left on the side of the road.

“We’ve seen some that have been executed on site, with bullet holes in the ground; the rest were tortured and executed somewhere else and dumped,” Johnson said.

The recent assertion by U.S. soldiers here that Iraq is in a civil war is a stunning indication that American efforts to bring peace and democracy to Iraq are failing, more than three years after the toppling of dictator Saddam Hussein’s regime.

U.S. hopes for victory in Iraq hinge principally on two factors: Iraqi security forces becoming more competent and Iraqi political leaders persuading armed groups to lay down their weapons.

But neither seems to be happening. The violence has increased as Iraqi troops have been added, and feuding among the political leadership is intense. American soldiers, particularly the rank and file who go out on daily patrols, say they see no end to the bloodshed. Higher ranking officers concede that the developments are threatening to move beyond their grasp.

“There’s no plan – we are constantly reacting,” said a senior American military official, who spoke on the condition of anonymity. “I have absolutely no idea what we’re going to do.”

The issue of whether Iraq has descended into civil war has been a hot-button topic even before U.S. troops entered Iraq in 2003, when some opponents of the war raised the likelihood that Iraq would fragment along sectarian lines if Saddam’s oppressive regime was removed. Bush administration officials consistently rejected such speculation as unlikely to come to fruition.

On Thursday, however, two top American generals told the Senate Armed Services Committee that Iraq could slip into civil war, though both stopped well short of saying that one had begun.

Political sensitivity has made some officers here hesitant to use the words “civil war,” but they aren’t shy about describing the situation that they and their men have found on their patrols.

“I hate to use the word “purify,’ because it sounds very bad, but they are trying to force Shiites into Shiite areas and Sunnis into Sunni areas,” said Lt. Col. Craig Osborne, who commands a 4th Infantry Division battalion on the western edge of Baghdad, a hotspot of sectarian violence.

Osborne, 39, of Decatur, Ill., compared Iraq to Rwanda, where hundreds of thousands of people were killed in an orgy of inter-tribal violence in 1994. “That was without doubt a civil war – the same thing is happening here.

“But it’s not called a civil war – there’s such a negative connotation to that word and it suggests failure,” he said.

The idea that U.S. forces have been unable to prevent the nation from sliding into sectarian chaos troubles many American military officials in Iraq.

Lt. Col. Chris Pease, 48, the deputy commander for the 101st Airborne’s brigade in eastern Baghdad, was asked whether he thought that Iraq’s civil war had begun.

“Civil war,” he said, and then paused for several moments.

“You’ve got to understand,” said Pease, of Milton-Freewater, Ore., “you know, the United States Army and most of the people in the United States Army, the Marine Corps and the Air Force and the Navy have never really lost at anything.”

Pointing to a map, 1st Lt. Robert Murray, last week highlighted a small Shiite village of 25 homes that was abandoned after a flurry of death threats came to town on small pieces of paper.

“The letters tell them if they don’t leave in 48 hours, they’ll kill their entire families,” said Murray, 29, of Franklin, Mass. “It’s happening a lot right now. There have been a lot of murders recently; between that and the kidnappings, they’re making good on their threats. … They need to learn to live together. I’d like to see it happen, but I don’t know if it’s possible.”

Riding in a Humvee later that day, Capt. Jared Rudacille, Murray’s commander in the 4th Infantry Division, noted the market of a town he was passing through. The stalls were all vacant. The nearby homes were empty. There wasn’t a single civilian car on the road.

“Between 1,500 and 2,000 people have moved out,” said Rudacille, 29, of York, Pa. “I now see only 15 or 20 people out during the day.”

Staff Sgt. Wesley Ramon had a similar assessment while on patrol between the Sunni town of Abu Ghraib and Shula, a Shiite stronghold. The main bridge leading out of Shula was badly damaged recently by four bombs placed underneath it. Military officials think the bombers were Sunnis trying to stanch the flow of Shiite militia gunmen coming out of Shula to kill Sunnis.

“It’s to the point of being irreconcilable; you know, we’ve found a lot of bodies, entire villages have been cleared out, we get reports of entire markets being gunned down – and if that’s not a marker of a civil war, I don’t know what is,” said Ramon, 33, of San Antonio, Texas.