As seen through a night-vision device, U.S. Marine Corps Sgt. Jodi Esp scans for simulated targets during a tail gun live-fire exercise in an undisclosed location in Southwest Asia, Dec. 20, 2015. Esp is a crew chief assigned to Marine Medium Tiltrotor Squadron 268, Special Purpose Marine Air-Ground Task Force-Crisis Response-Central Command. U.S. Marine Corps photo by Lance Cpl. Clarence Leake