A coordinated string of four bomb attacks within seven minutes killed at least 18 people and wounded 39 in northern Iraq on Tuesday, while a Baghdad car bomb injured 28, officials said, ending a relative lull in violence that had fallen over the country in recent days.
Hundreds of United States and Iraqi soldiers descended on the remote northern city of Tal Afar near the Syrian border on Tuesday, launching a major operation against insurgents following weeks of attacks against Iraqi security services there, military officials said.
Two US Marines died on Monday after separate roadside bombings near Fallujah, 65 km west of Baghdad, the military said.
Tuesday's attacks in northern Iraq appeared coordinated and aimed at checkpoints manned by members of Iraq's fledgling army, which has been a constant target of insurgents opposed to the country's new US-backed government.
The first explosion, caused by a roadside bomb, rocked Hawija, about 65 km southwest of Kirkuk, at around 9:30 am.
Soon after, three suicide bombers waiting in lines of cars at army checkpoints to the west and north of Hawija struck in quick succession.
In the deadliest attack, 10 civilians and one soldier were killed at a checkpoint in Dibis, three km west of Hawija, army Lieutenant Faleh Ahmed said.
Three soldiers and two civilians were killed at a checkpoint in Bagara, five km west of Hawija and two soldiers died in a suicide attack on the Aziziya checkpoint at the northern entrance to Hawija.