U.S. Pulling Out Troops in Iraq : Persian Gulf: Some of the 40,000 GIs move into a demilitarized zone to await U.N. peacekeepers. Officials say civilians may take shelter in the buffer area.

Ending its Gulf War occupation of Iraq, the United States on Sunday began moving the last of its troops out of the Euphrates River Valley and into a buffer zone along the Iraq-Kuwait border, American military officials announced.

The estimated 40,000 U.S. combat troops who remained in Iraq started withdrawing around 4 p.m. local time, signaling the end of 45 days of occupation, the U.S. Central Command in Riyadh said.

Thousands of Iraqi civilians who sought protection from American troops will also be allowed to relocate in the buffer zone, which will be controlled by the United Nations, Central Command spokesmen said.

The pullout from the sparsely populated desert and tiny towns of southern Iraq follows Baghdad’s formal acceptance Thursday of a U.N. cease-fire ending the Persian Gulf War. The speed of the pullout announcement appears to reaffirm the Bush Administration’s determination to keep out of further, potentially deadly entanglements in Iraq’s civil turmoil.

Once the withdrawal of American troops from Iraq is complete, Central Command headquarters is expected to shut down. Overall U.S. troop strength, meanwhile, dropped below 300,000 Sunday, down from a wartime high of 540,000.

Nevertheless, U.S. warplanes will continue to fly combat patrol missions to protect the troops as long as they are on the ground in Iraq, officials said.

Fewer than half of the troops now withdrawing from southern Iraq will move into the border demilitarized zone and remain there until a U.N. peacekeeping contingent is in place. The latter process began Saturday and is expected to take at least two weeks, officials said.

Most of the troops now pulling out of the occupied zone will continue on to Saudi Arabia for immediate deployment home, military officials said.

“The significance of this is we are pulling out of Iraq,” said Lt. Col. Mike Gallagher, spokesman for the Central Command. He added that the move into the demilitarized zone will take a “few days.”

The border buffer is an area nine miles wide, six miles on the Iraqi side of the frontier and three miles on the Kuwaiti side.

American troops have occupied roughly 15% of Iraq, taking up positions in the Euphrates River Valley south of Safwan, since defeating the army of Iraqi President Saddam Hussein. President Bush ordered a halt to fighting Feb. 28.

It was in U.S.-occupied Iraq that the first round of cease-fire talks between Desert Storm commander Gen. H. Norman Schwarzkopf and a delegation of Iraqi military commanders was held. And it was in U.S.-occupied Iraq that American GIs had to contend with the aftermath of Iraq’s civil war.

In announcing the withdrawal, U.S. officials sought to allay fears that an estimated 30,000 Iraqi civilians who flocked to the care of American soldiers would be abandoned.

Many of the sick and hungry refugees, who fled fighting between government troops and pro-Shiite rebels in the south, have said they fear reprisals from Hussein’s regime.

Most of the refugees will be allowed to move into the U.N.-controlled area, and withdrawing troops are offering to help them relocate, the Central Command said. Those who choose to stay in the Safwan area will be given supplies of food and water, a military source said.

News of the American pullout was also made public in Washington by Defense Secretary Dick Cheney, who confirmed that the withdrawal includes the refugees.

“The President gave instructions, which we conveyed to Gen. Schwarzkopf (on Saturday), to withdraw U.S. forces from the Euphrates area, from that area of southern Iraq that we’ve been occupying, and to withdraw to the buffer zone that is specified in the cease-fire resolution,” Cheney said on NBC’s “Meet the Press.”

He added that refugees who do not want to remain in Iraq will accompany the troop withdrawal “to make certain that they are inside the buffer zone themselves.”

“We are not going to leave refugees to the tender mercies of the Iraqis,” Cheney declared. “ . . . We clearly are not going to withdraw and end the effort in a way that leaves those people vulnerable or results in more deaths than might otherwise occur.”

About 5,000 refugees are camped at Sabba, three miles into Iraq from the Saudi Arabian border but some distance from the demilitarized zone. Central Command officials in Riyadh said that this group will remain “under the care and protection of the coalition forces until the refugees are moved to a more suitable location.”

The last troops in Iraq were members of two heavily armored divisions belonging to the U.S. VII Corps: the 1st Infantry Division and the 3rd Armored Division. Immediately after the Gulf fighting was halted, more than 200,000 troops occupied Iraq; they have been trickling out in recent weeks, with the U.S. XVIII Corps beginning to withdraw last month.

The first elements of the VII Corps began leaving early this month and accelerated their departure as the formal cease-fire went into effect Thursday. By the weekend, only about 40,000 soldiers remained, according to commanders in the field.

Central Command spokesmen refused to say how many troops would be left in the buffer zone, but a top-ranking military source said a division-size force of about 10,000 to 15,000 would stay behind.

The Army “felt they could cover it with a division,” the source said. “We’ve been wanting to do this for some time. When you are up there, you tend to attract people.”

Indeed, American checkpoints in occupied Iraq have seemed like magnets drawing a steady flow of displaced and fearful Iraqi civilians. In addition, thousands of men claiming to be Iraqi soldiers have presented themselves to be taken prisoner.

The problem of caring for a growing number of Iraqis was only one of the reasons that the United States was eager to get out of southern Iraq. Many GIs were demoralized by the horrors they heard were being committed by Hussein’s army. And the potential for being drawn into armed conflict was a worrisome prospect for some commanders.

Meanwhile, the job of policing the new demilitarized zone now falls to the so-called blue helmets--troops of many countries operating under the flag of the United Nations.

The commander of the U.N. peacekeeping force, Austrian Lt. Gen. Gunther Greindl, arrived in Kuwait on Saturday and met Sunday with the emir, Sheik Jabbar al Ahmed al Sabah. He was scheduled to go to Baghdad today.

Greindl told reporters that he expected 300 U.N. military observers to start arriving today. The contingent will eventually number 1,440 people from 31 nations and be headquartered in the Iraqi port and naval base of Umm al Qasr.

Times staff writer Karen Tumulty, in Washington, contributed to this report.