Iraqi forces launched their biggest security crackdown since the fall of Saddam Hussein with the start of Operation Lightning on Sunday, a sweep by 40,000 Iraqi troops who will seal off Baghdad and hunt for insurgents. Backed by the 10,000 US troops in the capital, Iraqi soldiers will block major routes into Baghdad and search the city district by district, looking for foreign Arab fighters and Iraqi guerrillas, Iraqi officials say.
But by Sunday evening, there were few signs of a heightened security presence in Baghdad, although checkpoints were set up in the north and south of the city and cars were searched. And insurgent attacks killed at least nine Iraqis in the capital.
Officials said the operation would gather steam in the coming days.
"The operation began today. The troops will block all entrances of Baghdad to prevent terrorists from conducting activities in the capital. It's a crackdown on the terrorism infrastructure," a Defence Ministry official told Reuters.
The operation was announced on Thursday - potentially giving insurgents the chance to flee Baghdad before it began.
Insurgents kept up their offensive on Sunday. Gunmen ambushed a car carrying Iraqi soldiers south of Baghdad, killing six troops, police said.
In Baghdad, insurgents fought gunbattles with police in the west of the capital. Hospital officials said three people were killed, including two police. Two suicide car bomb attacks in the capital, one near the oil ministry and the other targeting a police patrol, killed at least six Iraqis, police said.
In the town of Tuz Khurmatu south of Kirkuk, a suicide car bomber blew up his vehicle near an American military convoy, killing at least two Iraqis.
Witnesses said some US casualties were evacuated from the scene by helicopter, but the US military had no immediate information on the attack.
In Madaen, a mixed Sunni-Shia town south-east of Baghdad, a car bomb killed two policemen.
Near the town of Amara in mainly Shia southern Iraq, insurgents attacked a British military patrol, killing a British soldier, the Ministry of Defence in London said.
The US military announced the deaths of two more servicemen. A Marine was killed on Saturday in a roadside bomb attack on his vehicle in western Iraq and an American soldier died on
Friday after being wounded by a roadside bomb the previous day south-west of Baghdad.