Navy and the under secretary of the Navy. The U.S. Marine Corps itself is led by the commandant of the Marine Corps and the assistant commandant of the Marine Corps, both generals who are advised by the sergeant major of the Marine Corps. The Marine Corps statutory mission is outlined in and as originally introduced under the National Security Act of 1947, with its three primary areas of responsibility including: Seizure or defense of advanced naval bases and other land operations to support naval campaigns; Development of tactics, technique, and equipment used by amphibious landing forces in coordination with the Army and Air Force; and Such other duties as the President or Department of Defense may direct. Fleet Marine Force The combat power of the Marine Corps is centralized in the Fleet Marine Force (FMF), which itself is organized into Fleet Marine Force Atlantic, to support the U.S. Navy's Fleet Forces Command, and Fleet Marine Force Pacific, which supports the U.S. Navy's U.S. Pacific Fleet. The basic Marine Corps unit for conducting operations is the Marine Air-Ground Task Force (MAGTF), which combines Marine Corps and Navy land, air, sea, and cyberspace capabilities into a single command. There are three different sized variants of a Marine Air-Ground Task Force, but each consists of a command element, ground combat element, aviation combat element, and logistics combat element. A Marine ground combat element (GCE) is centered around Marine infantry, typically armed with a M27 Infantry Automatic Rifle. Unlike the Army, the Marine Corps does not train their own combat medics, relying on the Navy to provide hospital corpsman. These infantry units are supported by Marine Corps combat engineers, who conduct engineer reconnaissance, obstacle system emplacement, and breaching operations, and Marine Corps Force Reconnaissance teams. While the Marine Corps no longer operates its own tanks, opting to request support from the Army if needed, it maintains Light Armored Reconnaissance Battalions which operates the LAV-25 amphibious armored reconnaissance vehicle. Assault Amphibian Battalions operate the Assault Amphibious Vehicle and Amphibious Combat Vehicle, which enable the ground combat element to conduct amphibious landing operations. Marine Corps artillery operates the M777 howitzer and the M142 HIMARS, both supporting the ground combat element and the Navy at sea by striking enemy ships. The Marine aviation combat element (ACE) is the operational arm of Marine Corps Aviation, working to support the ground combat element. The F-35B Lightning II and AV-8B