The earliest origins of United States Army Japan can be traced to General
Douglas MacArthur's assumption of command of U.S. Army Forces in the Far East. In July 1941, USAFFE was established in Manila. The command was destroyed as the U.S. were defeated in the
Japanese invasion of the Philippines. After the end of the Second World War, the Army Forces Far East title was resurrected as the land forces element of the
Far East Command in Tokyo. When Far East Command was disestablished in 1957, several smaller U.S. Army commands were created. U.S. Army Japan (USARJ) first appeared on 1 July 1957 as a major subordinate command of
United States Army Pacific (USARPAC) in Hawaii. Reorganized in September 1968, USARJ employed a new structure to maximize operational efficiency, while keeping its existing missions and functions. In May 1972, the reversion of Okinawa to Japanese control resulted in the realignment of the Army's Pacific commands, with HQ USARJ absorbing elements for Okinawa, adjusting the command chain.
IX Corps was transferred from Okinawa, and collocated with this command, to become HQ USARJ/IX Corps. In July 1974, a USARJ reorganization established three subordinate commands: U.S. Army Garrison, Honshu (USAGH); U.S. Army Garrison, Okinawa (USAGO); and the U.S. Army Medical Department Activity-Japan, (MEDDAC-JAPAN). In January 1975, with the discontinuance of USARPAC, USARJ was designated a major Army command, reporting directly to the Department of the Army. In August 1990, USARPAC was reestablished. USARJ became a major subordinate command of that headquarters, as well as continuing as the Army Component Command of U.S. Forces, Japan (USFJ). In 1994, IX Corps was replaced by
9th Theater Army Area Command. In November 1999, it was redesignated the 9th Theater Support Command (TSC). There were several minor reorganizations and redesignations over the next decade, so that by September 2001, USARJ consisted of logistics bases in Japan and Okinawa. In September 2007, the 9th TSC was inactivated. In December 2007,
I Corps (Forward) was activated in Japan in line with the Army's transformation efforts. USARJ remains headquartered at Camp Zama, where it engages in numerous bilateral activities with the Japan Ground Self-Defense Force (JGSDF), and performs duties as
United States Forces Japan's Army Component Command. Command of the
78th Signal Battalion remained with the Hawaii-based
516th Signal Brigade (formerly 1106th) and operational control remains with the commander, USARJ/9th TAAC and since December 2007, USARJ/I Corps (Forward). On 11 March 2011, a devastating magnitude 9.0 earthquake and tsunami struck the northeast coast of Japan. Within minutes, USARJ began humanitarian assistance and disaster relief operations in support of the JGSDF during
Operation Tomodachi, Japan's largest-ever bilateral operation. USARJ supported the affected people after operations officially ended, by providing equipment and maintenance support to the JGSDF until September. == Notes ==