form a Northwestern TVD headquarters on the basis of the Staff of the Leningrad Military District. In their most modern form, High Commands for the TVDs were first reestablished in February 1979 for the Far East. Harrison wrote in the 2020s that the new command encompassed the Far East Military District and the Transbaikal Military District. An official military encyclopedia published after the Fall of the Soviet Union stated, said Harrison, that the Soviet Pacific Fleet, an air army, and an air defence corps were also operationally subordinated to the new formation; and that the high command "coordinated" with the armies of Vietnam, Laos, Cambodia, and Mongolia. The headquarters was set up at Ulan-Ude, near Lake Baikal. The RAND Corporation said in 1984 that the Soviet air and ground forces in Mongolia [subordinate to the Transbaikal Military District] and elements of the Mongolian Ground Forces and Mongolian Air Force were also at its disposal. In September 1984 three more High Commands were established: the Western (HQ Legnica), South-Western (HQ Kishinev), and Southern (HQ Baku) United States The term theater of operations was defined in the American field manuals as the land and sea areas to be invaded or defended, including areas necessary for administrative activities incident to the military operations (chart 12). In accordance with the experience of World War I, it was usually conceived of as a large land mass over which continuous operations would take place and was divided into two chief areas—the combat zone, or the area of active fighting, and the communications zone, or area required for administration of the theater. As the armies advanced, both these zones and the areas into which they were divided would shift forward to new geographic areas of control. See also Battlespace China Burma India Theater European Theater of Operations European theatre of World War II AfPak Locus of control Unified Combatant Command Western Theater of the American Civil War Formations of the Soviet Army References Warfare