Marine Corps Sgt. Travis Bell scans for threats during Integrated Training Exercise 2-15 on Marine Corps Air Ground Combat Center Twentynine Palms, Calif., Feb. 18, 2015. Bell is a door gunner assigned to Marine Light Attack Helicopter Squadron 169. (U.S. Air Force photo by Master Sgt. Donald R. Allen)

More images of Marines during Integrated Training Exercise 2-15 in the slideshow below.