The primary mission of the Marine Security Guard (MSG) is to provide internal security at designated U.S. diplomatic and consular facilities in order to prevent the compromise of classified material vital to the national security of the United States. The secondary mission of the MSG is to provide protection for U.S. citizens and U.S government property located within designated U.S. diplomatic and consular premises during exigent circumstances (urgent temporary circumstances which require immediate aid or action).
Marine Corps Embassy Security Group (MCESG) Region Commands report to the Commanding Officer of MCESG and exercise command, less operational supervision, of Marines assigned to the Marine Security Guard (MSG) detachments in their respective regions. The MCESG Region Headquarters ensure the continued training, operational readiness, personnel administration, logistical support, as well as the morale, welfare, and discipline of Marines assigned for duty to MSG detachments at designated U.S. diplomatic missions in order to support the Department of State in the protection of classified material at foreign posts.
The Commanding Officer of MCESG reports to the Commandant of the Marine Corps (CMC), exercising command, less operational supervision, of Marines assigned to MSG detachments. MCESG Headquarters is responsible for the screening, training, assignment, administration, logistical support of Marine Corps unique items, and discipline of Marines assigned to MCESG. The Commanding Officer, MCESG also commands those Marines assigned to Headquarters, MCESG, and MCESG regional headquarters, and is the Director, MSG School. MSG School provides suitability screening and formal training for selected Marines to perform duties as MSGs at foreign Service Missions.