U.S. Marines with 9th Communication Battalion, I Marine Expeditionary Force Headquarters Group react to a simulated Improvised Explosive Devices (IED) while on a mounted patrol during Operation Vigilant aboard Camp Pendleton, Calif., Mar. 7, 2014. Operation Vigilant was conducted to sustain and build proficiency in mounted and dismounted patrolling techniques, Counter IED training, and Military Operation in Urban Terrain. (U.S. Marine Corps photo by Cpl Ismael E. Ortega, 1st Marine Division / Released)