The sand blows across this isolated patch of desert, flecks of moving rock and dust. When the heat grows unbearable, as it often does, the men hover inside white tents, the canvas sides partially rolled and tied off. When day settles into evening, and the air is more forgiving, the young men come out to play soccer and volleyball under the red desert moon. The old ones gather in groups and pray.

Sometimes both young and old move toward the shiny new chain-link fence that surrounds the tents. They clutch the wires with their dark hands and look out. There is little to see but fuel trucks in the distance and the metal cranes towering over the nearby port of Umm Qasr.

The men are prisoners -- Iraqis brought to this desolate spot 300 miles southeast of Baghdad where the U.S. Army has established a detention facility called Camp Bucca. Set up last year during the invasion of Iraq, the camp was named for Ron Bucca, a New York fire marshal and Army Reservist who died in the Sept. 11, 2001, attack on the World Trade Center. Envisioned as a temporary place to hold Iraqi prisoners of war, the camp was emptied and closed by December. But Iraq's postwar insurgency created the need for a place to house thousands of suspected insurgents, and commanders turned to Camp Bucca to supplement the facilities at Abu Ghraib prison outside Baghdad.

This week, a resolution adopted unanimously by the U.N. Security Council granted the U.S.-led occupation force "the right to detain Iraqis viewed as a security threat." That approval, contained in a security agreement between the United States and Iraq's new interim government, essentially settled the future of Camp Bucca. It will be the primary detention facility for people still in U.S. custody after the interim government takes power at the end of the month, and it is expected to hold between 2,000 and 2,500 detainees, officials have said.

"From the perspective of leaders responsible for the facility, it was always assumed it would be used in one form or another, so there was a continuing investment in the quality of life for the soldiers and the quality of care for detainees," said Col. David Quantock, commander of the 16th Military Police Brigade, which has soldiers at both Camp Bucca and Abu Ghraib.

The U.S. military decided last month to vacate Abu Ghraib and send all the prisoners held there to Camp Bucca. Military officials were eager to distance themselves from Abu Ghraib, where former president Saddam Hussein's security forces tortured and executed tens of thousands of prisoners and where cameras captured U.S. soldiers beating and humiliating detainees last fall. But Iraqi leaders rejected the plan, so both facilities will now remain open, with Abu Ghraib serving primarily as a processing center, with about 1,500 prisoners, Maj. Gen. Geoffrey D. Miller, deputy commander of detainee operations in Iraq, said in an interview.

In an Army investigation into abuses at Abu Ghraib, Maj. Gen. Antonio M. Taguba found that soldiers "committed egregious acts and grave breaches of international law" both there and at Camp Bucca. Amnesty International reported last summer that detainees at Camp Bucca "were held in tents in the extreme heat and were not provided with sufficient drinking water or adequate washing facilities. They were forced to use open trenches for toilets and were not given a change of clothes -- even after two months' detention."

Considerable improvements have been made since then. For one, the prison population at Camp Bucca has dropped from 8,000 at its peak last fall to about 2,700 last week. Detainees are given hot meals and showers, recreation time and cigarettes for work details. Medical personnel visit the compounds every day to hand out pills and diagnose ailments. The prisoners are allowed family visits, and last week soldiers began taking photographs during the visits. A prisoner's family gets one copy to take home and another copy is left with the detainee.

The responsibility for improving U.S. detention facilities in Iraq falls to Miller, who flew last week from Baghdad to Camp Bucca to meet with the commanders and to inspect the complex. As he toured the camp, his boots kicking up dust, Miller asked questions and offered suggestions.

"Are we giving the detainees bottled water?" he asked. Noticing a pile of sleeping bags stacked below a guard tower, Miller wanted to know if all of the detainees had been given sleeping bags. The answer was yes. "Good," he said. "Wonderful."

Miller, who ran the military detention facility at Guantanamo Bay, Cuba -- known as Gitmo -- said Camp Bucca presented a very different set of challenges. "This is a complex business," he said. "Gitmo is different because this population is a relatively small number of terrorists. It's not the same level of evil."

During Miller's visit, commanders showed him an area where workers were constructing large metal cages to replace the tattered tents in the isolation compound for prisoners who had been caught fighting or found with contraband.

Miller walked over to the cages, peered in, shook his head and said finally: "Guys, these don't sing to me. I don't like it. You can't put people in here."

The lives of the soldiers at Camp Bucca have improved over the past year, as well. The dining facility, dubbed the Bucca Inn, is considered among the finest on any base in Iraq. Soldiers sleep in air-conditioned trailers and tents. There are hot showers, a recreation facility and a post office -- amenities that did not exist last summer.

"We come down here, we do what we have to do," said Spec. Douglas Kocian, a tower guard from the 107th Field Artillery Regiment based in Pittsburgh. "Nobody wants to be here, but I think everybody is coping with it the best they can. It's not exciting. I'm not saying I'm the happiest camper, but my wife isn't happy, either."

On a recent morning, Kocian watched from the guard tower as prisoners below lined up for medical call.

Some wore tribal dress, others pants and loose shirts. A few were wrapped only in towels as they scurried to the shower house set up inside the compound.

"We all recognize we could be in a lot worse places in Iraq," said Capt. Erik Fessenden, commander of Marauder Company, 172nd Field Artillery, based in Manchester, N.H.

Fessenden's company came to Camp Bucca in late February. Its 178 members serve as exterior guards for the camp and as convoy escorts.

"We're stretched thin -- long, 12-hour shifts -- and the weather conditions, you can see the blowing sand," he said. "There have been some long days."

Fessenden said he had little to tell his soldiers about what was coming next.

"I think there are still a lot of unknowns for exactly how things will flush out," he said. "The plans have changed. I don't think a lot of people can tell you. We're preparing for things to get more dangerous down here and more heat.

"But it's difficult to predict where it's going, to be honest with you."