U.S. Marine Corps ground crew, Marine Attack Squadron 214, Camp Pendleton, Calif., perform pre-flight checks on an AV-8B Harrier during Integrated Training Exercise 2-15 at Marine Corps Air Ground Combat Center (MCAGCC) Twentynine Palms, Calif., Feb 13, 2015. MCAGCC conducts relevant live-fire combined arms training, urban operations, and Joint/Coalition level integration training that promotes operational forces readiness. (U.S. Air Force photo by Technical Sgt. Daniel St. Pierre/Released)