TRACER TRAINING U.S. Army soldiers fire .50-caliber machine gun rounds at the base of a training target to indicate to nearby helicopters where to fire their rockets during partnered aerial-ground integration training between U.S. and Iraqi forces on Al Asad Air Base, Iraq, May 21, 2010. The soldiers are assigned to the 558th Military Police Company. SHARE: Download: Full Size (0.06 MB) Credit: VIRIN: 981345-M-RHT67-295.jpg Photo Gallery