Two U.S. soldiers were killed when their helicopter was shot down and crashed in central Iraq, the military said Friday, as the government prepared to ring Baghdad with tens of thousands of security forces to curb the rampant insurgency.
U.S. officials were investigating Thursday's crash of a two-seat OH-58 Kiowa helicopter near Buhriz, a former Saddam Hussein stronghold about 60 kilometers (35 miles) north of Baghdad.
The armed U.S. reconnaissance helicopter was supporting combat operations. The slain soldiers were with Task Force Liberty, under the command of the Tikrit-based 42nd Infantry Division.
The military said small-arms fire downed the helicopter, while another returned to base safely despite being hit.
At least 1,652 members of the U.S. military have died since the beginning of the Iraq war in March 2003, according to an Associated Press count.
Iraqi authorities are preparing the largest show of force in the capital since Saddam's ouster in a bid to halt increasing militant attacks, which have killed more than 650 people since the country's new government was announced April 28.
More than 40,000 Iraqi police and soldiers, backed by American troops and air support, will set up hundreds of checkpoints, raid houses and search vehicles as part of "Operation Lightning," Iraqi's interior and defense ministers announced Thursday.
In a reminder of the deadly insurgency, violence claimed at least 15 lives Thursday across Iraq, including a car bomb blast in Baghdad's northern Shula suburb that exploded near a police patrol, killing five people.
Another ambush targeting a police patrol, this time in the northern Iraqi city of Mosul, killed one policeman and a bystander caught in the crossfire Friday, said police Brig. Saeed Ahmed.
A guard at an Azamiyah carpentry factory in northern Baghdad was killed Friday when four mortar rounds landed on the building, said police 1st Lt. Sadoun Abdul Ridha. Four others were wounded.
Insurgents destroyed several sections of an oil pipeline on Baghdad's western outskirts, near Abu Ghraib, on Friday, and footage taken by Associated Press Television News showed jet black billowing clouds of smoke towering into the sky.
In Najaf, Oil Minister Ibrahim Bahr al-Uloum met with top Shiite cleric Grand Ayatollah Ali al-Sistani and said the government will build an oil refinery in the southern Shiite city.
"We will start soon a project of an oil refinery in Najaf," al-Uloum told reporters.
Iraqi authorities did not say how long Operation Lightning would last, and it was uncertain whether the Iraq security services are capable of mounting a sustained operation.
Iraq has 89,400 security personnel, including commando units, in the Interior Ministry, according to the U.S. military. The figure may include some deserters. Another 75,800 forces are in the Iraqi military, mostly the army.
"We will establish, with God's help, an impenetrable blockade surrounding Baghdad like a bracelet surrounds a wrist," Defense Minister Saadoun al-Duleimi said.
Baghdad will be divided into two sectors, Karkh on the west bank of the Tigris River that separates the city, and Risafa on the east. Karkh will be split into 15 sub-districts and Risafa into seven. Security forces will operate 24 hours a day.
Iraqi police forces announced breakthroughs Friday in three car bomb attacks carried out this month, including Thursday's Shula bombing.
Police paraded three men, including two brothers, before reporters on Friday who confessed to carrying out Monday's car bomb attack outside an eastern Baghdad restaurant popular with police that killed at least eight people.
Army official Sadiq Jaafar said police raided two Baghdad homes overnight and detained four suspects, including three brothers, over the Shula bombing, which also wounded 17 people, said army Staff Brig. Sadiq Jaafar.
Wasit police commander Maj. Gen. Abdul al Ameer said several people were detained Friday in connection with a May 6 car bomb attack at a market in Suwayrah, 40 kilometers (25 miles) south of Baghdad, that killed 17 people.
Northwest of Baghdad, in the city of Haditha, more than 1,000 U.S. troops continued a sweep for insurgents responsible for attacks against coalition troops, ordering at least one airstrike Thursday against a suspected militant position. At least 11 insurgents and one Marine have been killed since the mission began Wednesday.
Some insurgents in Haditha are believed loyal to Iraq's most-wanted militant, Abu Musab al-Zarqawi, whose fate has been the subject of intense speculation this week.
The Iraqi interior and defense ministers said Thursday the Jordanian-born leader of al-Qaida in Iraq had been wounded, confirming several Internet statements making the same claim this week. An Internet statement also claimed the group had appointed a deputy to fill in for al-Zarqawi. But a rival statement rejected the claim.
American authorities, meanwhile, are investigating the killing of three Iraqis by U.S. soldiers who shot at their van in southeastern Baghdad on Thursday, military spokesman Master Sgt. Greg Kaufman said.
Soldiers shot at the vehicle after its driver failed to respond to warnings to stop, Kaufman said. Soldiers had seen several Iraqis flee in the vehicle after acting suspiciously near a car tire on the road, raising suspicions they may have been planting a roadside bomb. No explosives were found.
Police Sgt. Najim Aboud said two of the slain Iraqis were brothers, and their mother also was in the van.
SAMEER YACOUB, Associated Press Writer