In the United States Marine Corps, a Marine Air–Ground Task Force is the principal organization for all missions across the range of military operations. MAGTFs are a balanced air–ground, combined arms task organization of Marine Corps forces under a single commander that is structured to accomplish a specific mission. The MAGTF was formalized by the publishing of Marine Corps Order 3120.3 in December 1963, "The Marine Corps in the National Defense, MCDP 1-0". It stated:A Marine Air–Ground Task Force with separate air ground headquarters is normally formed for combat operations and training exercises in which substantial combat forces of both Marine aviation and Marine ground units are included in the task organization of participating Marine forces.