BAGHDAD – U.S. aircraft dropped leaflets seeking information about three U.S. soldiers feared captured by al-Qaida, as troops intensified the search Tuesday despite a warning from the terror group that the hunt will endanger the captives’ lives.

The U.S. command said the searchers were trying to isolate areas where they suspect the captives may have been taken after the pre-dawn ambush Saturday in which four American troops and an Iraq soldier were killed.

“The captors don’t have freedom of movement,” said Maj. Kenny Mintz of San Diego. “If they have the soldiers, they can’t move them from where they are. We’re doing a deliberate search of the areas.”

On Monday, an al-Qaida front group – the Islamic State of Iraq – warned the Americans in a Web statement to call off the hunt “if you want their safety.”

The warning could indicate that the presence of about 4,000 U.S. and Iraqi troops in the thinly populated farming area 20 miles south of Baghdad is making it difficult for the captors to move the Americans to a secure location.

In a statement Tuesday, the U.S. command said American soldiers have questioned more than 450 people and detained at least 11 since the search began last weekend.

A later statement said aircraft had dropped leaflets asking for help in locating the soldiers. Trucks with loudspeakers were roaming the area urging people to come forward with any information. No details of the leaflets or their precise message were released.

On Tuesday, the military said the soldiers were assigned to Company D, 4th Battalion, 31st Infantry Regiment, which is part of the 10th Mountain Division from Fort Drum, N.Y.

At the time of the attack, the soldiers were in two vehicles “at a stationary observation post trying to interdict terrorists who place roadside bombs,” U.S. spokesman Lt. Col. Christopher Garver said.

“There were other observation posts that were trying to do this in the area. They were not moving in a convoy. The entire unit was out operating in this same area,” Garver added.

Al-Qaida and other insurgent groups have been active for years in the string of towns and villages south of the capital. The area is known as the “triangle of death” because of frequent attacks on U.S. and Iraqi forces as well as Shiite civilians traveling to shrine cities in the south.

Last June, al-Qaida claimed responsibility for the deaths of two U.S. soldiers whose mutilated bodies were later found in the same area.

The soldiers attacked last Saturday were assigned to a small patrol base set up as part of the new U.S. strategy to move troops from large, heavily defended garrisons to live and work among the people.

Critics of the strategy had warned that such small outposts are more vulnerable to attack. Last month, nine American soldiers were killed when a suicide bomber detonated his explosives-laden vehicle near a small patrol base northeast of Baghdad.

Last week, an embedded reporter for the Stars and Stripes newspaper, who visited the patrol base south of Baghdad, said the soldiers were housed in a rural home with protective razor wire “not far from the front door.”

“Soon after the base was established, insurgents began testing their new neighbors,” the Stars and Stripes said. “In the first months, one convoy came across seven roadside bombs piled outside the front gates. More recently, U.S. officials had gotten reports that a force of more than two dozen insurgents planned to storm the walls” although the attack never materialized.

The Pentagon confirmed the dead as Sgt. 1st Class James D. Connell Jr., 40, of Lake City, Tenn.; Pfc. Daniel W. Courneya, 19, of Nashville, Mich.; and Pfc. Christopher E. Murphy, 21, of Lynchburg, Va.

The four other soldiers are Sgt. Anthony J. Schober, 23, of Reno, Nev.; Spc. Alex R. Jimenez, 25, of Lawrence, Mass.; Pfc. Joseph J. Anzack Jr., 20, of Torrance, Calif.; and Pvt. Byron W. Fouty, 19, of Waterford, Mich. The Pentagon said one of those four was among the dead, but it could not confirm which one.

“I’m proud of my dad, because he didn’t really fight for himself, he fought for the country,” Connell’s teenage daughter, Courtney, told Knoxville’s WATE-TV.

In Michigan, students at Maple Valley High School created a memorial for Courneya, who graduated in 2005 and was well-known in the small community southwest of Lansing. He was a member of the school’s track and soccer teams and played clarinet in the band.

“It’s a tribute of photos, posters, plaques and a picture of him in his uniform,” school official Kelly Zank told The Associated Press on Tuesday.

Courneya’s mother, Wendy Thompson, said her husband, Army Spc. David Thompson, was in Iraq and returning home after learning of his stepson’s death.

Also Tuesday, President Bush chose Lt. Gen. Douglas Lute, the Pentagon’s director of operations and a former leader of U.S. military forces in the Middle East, to oversee the fighting in Iraq and Afghanistan as a war czar.

The appointment capped a difficult search for someone to fill the job, given the unpopularity of the Iraq war, now in its fifth year, and uncertainty about the clout the war coordinator would have.

Around Iraq on Tuesday, at least 51 people were killed or found dead. They included seven killed in a pair of bombings in Baghdad’s Tayaran Square shopping area and four who died when mortar shells struck the Shiite area of Sadr City.

Under a new government policy limiting media coverage of such tragedies, Iraqi police prevented news photographers and cameramen from filming the scene.

The government said the order, announced over the weekend, is aimed at preventing journalists from inadvertently tampering with evidence, protecting the privacy of the wounded and keeping insurgents and militias from keeping track of their success rate.

The ban also prevents pictures which call into question U.S. and Iraqi claims of success in quelling violence in Baghdad.

Elsewhere, five civilians were killed and 41 wounded when dozens of gunmen attacked a village north of the capital, Iraqi authorities said.

A mortar or rocket slammed into the U.S.-controlled Green Zone, wounding five American Embassy contractors, a spokesman said. U.S. Embassy spokesman Lou Fintor said there were no deaths and property damage was minimal. He said the contractors’ nationalities had “not yet been confirmed.”

Fintor said the embassy was “open and functioning normally.”