140813110501-iraq-bridge-15-horizontal-galleryKurdish forces fired mortars and explosives at extremist militants Sunday as the battle to retake a strategic dam in northern Iraq raged on. Smoke rose from the horizon, buildings were ablaze and the sound of massive explosions filled the air near Mosul Dam. By Sunday evening, the Kurdish forces — known as the Peshmerga — had taken over the eastern side of the structure, a spokesman for the group said. Clashes were ongoing over the western side, Peshmerga spokesman Halgord Hikmat told CNN. The forces face a daunting challenge: fighting a fierce offensive to retake the dam without damaging it. U.S. warplanes joined the effort amid growing concern that the facility is not maintained and could rupture, a U.S. official told CNN. MORE