Iraq ? In an old tactic of Sunni extremists, two suicide bombers set off explosives among Iraqi army recruits Tuesday in Baqouba, killing at least 28. Violence also flared in the northern city of Mosul, where a dozen people died in bombings that targeted the Iraqi police and army.

The attack in Baqouba, capital of Diyala province, came ahead of a planned Iraqi military offensive to halt attempts by militants to regroup in the volatile area northeast of Baghdad. Late Tuesday, the U.S. military said an American soldier was killed by a bomb while searching a house in the province Tuesday, but gave no other details.

Diyala is critical to Baghdad’s security because of its strategic importance as an entrance to the capital and a threat to supply routes going north. The ethnically mixed area also borders Iran, which the United States has accused of helping militants to stage attacks on American troops.

U.S. military officials said Tuesday’s attack did not reflect any increase in militant strength in the area.