No-man's land begins at Checkpoint Charlie, a fortified intersection on the southern edge of this embattled city.

Three U.S. tanks block the four-lane road leading past the abandoned Najaf Agricultural Research Institute. No vehicles are permitted in or out of the city, except for a single ambulance that is meticulously searched on each trip. Taxis, pickups and a city bus litter the landscape. All have been riddled with gunfire from fighting earlier this week, when Saddam's Fedayeen militia attacked in waves.

Heavy combat has given way to siege, punctuated by occasional mortar rounds and rocket-propelled grenades lobbed out of the city and airstrikes and artillery fired in. The 101st Airborne Division, reinforced with Abrams tanks, has moved forward to tighten the cordon north and south of Najaf, allowing troops from the 3rd Infantry Division to reposition for an eventual resumption of their drive toward Baghdad.

For now, the focus of the Army's V Corps is Najaf, a city holy to Shiite Muslims and now important to American commanders. A mosque in the city marks the burial place of Ali, son-in-law of the prophet Muhammad, and draws Shiite pilgrims from across the region. Wedged between a steep escarpment on the west and the Euphrates River on the east, Najaf is considered vital to securing routes to Karbala and the western approaches to Baghdad.

Some senior U.S. officers favor hammering military targets in Najaf, perhaps after giving an ultimatum to Fedayeen die-hards whose numbers are estimated at anywhere from a few hundred to a few thousand. Other senior officers favor slowly squeezing the town, over weeks if necessary, then rushing in humanitarian aid to make Najaf an example of American liberation and beneficence. All are puzzled by the absence of insurrection by Shiite Muslims, who in the wake of the Persian Gulf War 12 years ago rose in a bloody rebellion that was quashed by President Saddam Hussein.

Today, the noose was tightened on Najaf. In the north, the division's 2nd Brigade has fanned out on both banks of the Euphrates. Troops with support from U.S. tanks also hold the bridge at Kifl, a now eviscerated town just upstream from a large fork in the river where skirmishing and artillery exchanges continue as part of the battle for Najaf.

A long line of riflemen trudged past early this afternoon, each soldier moving with the rolling waddle characteristic of men dead-weighted with weapons, canteens, gas masks, knee pads, night vision goggles, flex cuffs, smoke canisters and other kit. Others took fighting positions along a reedy dike near Kifl.

"For some reason they want this town," Col. Joseph Anderson, the brigade commander, said today. "They're fighting for it. It's not like there's a million dollars in gold here. But they want it."

After a car bombing north of here killed four soldiers from the 3rd Infantry Division this morning, troops were suspicious of everything on wheels. "We're waving to them to stop, and if they don't stop, they'll get what's coming to them," Anderson said.

In the south, the 1st Brigade of the 101st is also squeezing Najaf. At Checkpoint Charlie, Capt. John Lauer, commander of a tank company attached to the 101st, gestured to his 14 Abrams tanks blocking approaches to the city.

"The general tactic has been for [the Iraqis] to drive out of the city with machine guns mounted in a vehicle or to jump out and shoot some small arms and RPGs, then take off," said Lauer, 28, from White Bear Lake, Minn.

A small group of prisoners was interrogated in the intersection late this afternoon. One prisoner in a gray robe said he had deserted from a Republican Guard division south of Karbala to come home to Najaf. "I hate the war, I hate the army, I hate Saddam Hussein," he said through an interpreter. Another prisoner said that Baath Party officials have been warning Najaf citizens that U.S. forces will soon leave Iraq, as they did after the 1991 Gulf War, leaving Iraqi insurrectionists on their own.

U.S. officers continue to assert that Hussein loyalists are forcing reluctant Iraqis to fight by threatening to kill their families. "It's tough to fight an enemy like that," Col. Lyle Cayce, the 3rd Division's chief lawyer, said today. "I find it ironic that this country which created the first legal system, the Hammurabi Code, is now abiding by no legal code."

In an abandoned school outside Najaf, officers in the 1st Brigade ponder the reduction of the city, wondering how to accomplish their mission while staying alive. A huge city map of Najaf hung from one classroom wall; the landmarks included theaters, markets, gas stations, a recreation complex, a power plant.

On the opposite wall was a hand-scrawled poster titled "March Madness 2003," with names from a former life penciled into the brackets: Texas, Michigan State, Kansas, Marquette, Arizona. Next to the door, a slogan in Arabic promised, "Plan well and the results will be good."