BAGHDAD, Iraq – U.S. commanders announced the start of a major offensive outside Baghdad on Saturday aimed at flushing out al-Qaida-linked fighters who use the lawless region to unleash attacks on the capital.

The offensive began before dawn Saturday and is expected to last several weeks, said Maj. Gen. Rick Lynch, commander of the Army’s 3rd Infantry Division, who oversees four provinces south of Baghdad.

The operation is in the region where three U.S. soldiers were captured in an ambush last month. The military reported Saturday that the identification cards of the two still-missing soldiers were recovered in a recent raid on a suspected al-Qaida-linked safe house north of Baghdad, 75 miles from the spot where the men disappeared.

But military spokesman Lt. Col. Christopher Garver said a search of the area yielded no evidence the missing soldiers had been held at the house where their IDs were found June 9.

The house also contained computers, video production equipment, rifles and ammunition, the military said in a statement. There was a gunfight as U.S. soldiers approached the building near Samarra, and two soldiers were injured. But no one was found inside, the statement said.

Spc. Alex R. Jimenez of Lawrence, Mass., and Pvt. Byron W. Fouty of Waterford, Mich., disappeared after an attack on their patrol May 12 outside Yousifiya, a town about 10 miles south of Baghdad. The body of a third soldier captured with them, Pfc. Joseph J. Anzack Jr. of Torrance, Calif., was later pulled from the Euphrates river nearby.

The Islamic State of Iraq, an insurgent umbrella group, later released a video claiming it had killed the three captives. The video included footage of the men’s IDs but offered no proof they were dead.

With pressure mounting in Washington, D.C., for results in Iraq, U.S. Defense Secretary Robert Gates arrived late Friday on a visit to assess progress implementing the security crackdown launched in February.

After being briefed by U.S. commanders and Ambassador Ryan Crocker, he met Iraqi leaders to press for action on reforms that U.S. officials believe will encourage reconciliation between the country’s warring ethnic and religious factions. They include a reversal of a ban on government jobs for members of Saddam Hussein’s Baath Party and a fair distribution of the country’s oil wealth.

Iraqi Prime Minister Nouri al-Maliki assured Gates that his government was “very serious” about reconciliation, according to a statement issued by his office. The prime minister also noted that Iraqi political and religious leaders had so far averted a major backlash after a revered Shiite shrine in Samarra was bombed Wednesday for the second time in just over a year.

In a sign of what could come, an explosion damaged the minaret of a Sunni Muslim mosque in the southern city of Basra, the second such attack in and around the overwhelmingly Shiite city in as many days. No casualties were reported.

In other developments, the remains of at least 13 members of an Iraqi tae kwon do team were found more than a year after the disappeared in Al Anbar, a violent province west of Baghdad, police and relatives said.

U.S. military deaths

Latest identifications reported by the military of U.S. personnel killed in Iraq:

Army Spc. Damon Legrand, 27, Lakeside, Calif.; died Tuesday in Baqubah of wounds from small-arms fire in Baghdad; assigned to the 571st Military Police Company, 504th Military Police Battalion, 42nd Military Police Brigade, Fort Lewis.

Air Force Lt. Col. Glade Felix, 52, Lake Park, Ga.; died Monday at Al Udeid Air Base, Qatar, of unknown causes; assigned to the 622nd Aeromedical Staging Squadron, Robins Air Force Base, Ga.

Marine Lance Cpl. Johnny Strong, 21, Waco, Texas; killed Tuesday in combat in Anbar province; assigned to the 2nd Battalion, 7th Marine Regiment, 1st Marine Division, Twentynine Palms, Calif.

Army Spc. Josiah Hollopeter, 27, San Diego, died Thursday in Balad of wounds suffered from small arms fire in Muqdadiyah; assigned to the 6th Squadron, 9th Cavalry Regiment, 3rd Brigade Combat Team, 1st Cavalry Division, Fort Hood, Texas.