U.S. Marines provide security for a CH-46E Sea Knight helicopter . U.S. Marines from the 13th Marine Expeditionary Unit provide security for a CH-46E Sea Knight helicopter during a joint mass casualty training exercise in Grand Bara, Djibouti, near Camp Lemonier on May 20, 2009. Marines from the unit trained with Guardian Angels from the 82nd Expeditionary Rescue Squadron during the day-long exercise. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 837836-A-RKZ77-596.jpg Photo Gallery