BAGHDAD — U.S.-led forces conducted a raid in the Baghdad neighborhood of Sadr City early today, killing three militants as they tried to break up a cell accused of smuggling weapons from Iran to fight U.S. forces, the military said.

The raid was part of the military's 12-week-old Baghdad security plan, meant to tackle the Sunni-led insurgents and Shiite militias and bring order to the Iraqi capital.

Just after midnight, a joint U.S.-Iraqi force on a raid in the southern part of the Shiite slum of Sadr City, came under fire from two buildings, the military said in a statement. After a gun battle, the soldiers called in an airstrike that killed three armed insurgents, it said.

The force was searching for a cell suspected of smuggling weapons from Iran, the military said.