BAGHDAD, Iraq – Iraq announced plans yesterday to deploy 40,000 police and soldiers in the capital and ring the city with hundreds of checkpoints “like a bracelet” in the largest show of Iraqi force since the fall of Saddam Hussein.

In a reminder of the difficulty Iraqi security forces face in stopping insurgent attacks, violence claimed at least 15 lives yesterday in Baghdad including a car bomb that exploded near a police patrol, killing five people and wounding 17.

Two American soldiers were killed last night when their helicopter was shot down near Baghdad, while another chopper was hit but landed safely, the U.S. military said.

The two pilots were the only ones aboard their aircraft when it went down, a military spokeswoman in Baghdad, Captain Patricia Brewer, said. She said their bodies have been recovered.

The two Task Force Liberty helicopters were struck by small arms fire at 10:50 p.m. after responding to troops in contact with enemy forces near Baqouba, 35 miles northeast of Baghdad, the military said.

A OH-58 Kiowa carrying two people landed safely at a nearby base after sustaining damage. The military didn’t say if there were any injuries aboard that aircraft.

In Baghdad, Prime Minister al-Jaafari told a small group of Western reporters that next week’s planned crackdown, dubbed Operation Lightning, was designed “to restore the initiative to the government.” Insurgents have killed more than 620 people since his government was announced on April 28.

“We will establish, with God’s help, an impenetrable blockade surrounding Baghdad like a bracelet surrounds a wrist,” Defense Minister Saadoun al-Duleimi said.

Iraqi authorities did not say how long the crackdown would last, and it was uncertain if the Iraq security services are capable of mounting a sustained operation. Except for a few elite units, most police officers are believed to have joined up for the higher pay the job provides – at $300 per month, their salaries are triple the average wage.

Iraq currently has 89,400 security personnel attached to the Ministry of Interior, according to the U.S. military. This includes police, highway patrol, and some commando units, although the figure may include some who have deserted. Another 75,800 forces are in the country’s military, most of them in the army.

Mr. al-Jaafari said his government was working hard to recruit, train, and equip its police and army, but still needed support from 160,000 foreign troops, including 138,000 from America, to deal with the raging insurgency.

American forces will back the Iraqis with logistical aid and air cover during Operation Lightning, according to the U.S. military.

Mr. al-Jaafari said all of Baghdad’s 23 entry points would be controlled. Interior Minister Bayan Jabr, who helped announce Operation Lightning, said there would be 675 checkpoints along with mobile checkpoints to try to deter assailants around the city and in areas where attacks are frequent. The government said Baghdad would be divided into two sectors, Karkh on the west bank of the Tigris River that separates the city, and Risafa on the east. Karkh would be divided into 15 subdistricts, and Risafa into seven subdistricts. Police and emergency personnel would operate in Baghdad 24 hours a day.

Mr. al-Duleimi, one of a handful of Sunni Muslims in the Shiite-led government, called on all Iraqis to stand up to an insurgency that has raged unabated for more than a year.

“We have the absolute belief that there is no place for the terrorists, there is no place for those who give shelter to the terrorists, or those who provoke terrorism,” he said. “We will stand solidly against anyone who tries to shed a drop of Iraqi blood, against anyone who tries to kill any Iraqi.”