The U.S. military launched a series of airstrikes in northern Iraq on Friday as American forces returned to action in Iraq to fight a brutal Sunni extremist force accused of attempting genocide in its bid to create a hard-line Islamic state. (Read the latest story on the airstrikes.)

U.S. fighter jets and armed drones attacked targets in Iraq for the first time since the American troop withdrawal in 2011 to try to halt the Sunni extremist advance on the Iraqi Kurdish capital of Erbil.

...