United States Army, Japan

United States Army, Japan (USARJ) consists of about 2,000 soldiers and is charged, during peacetime, with operating port facilities and a series of logistics installations throughout Honshū and Okinawa. USARJ participates actively with the Japan Ground Self-Defense Force in bilateral training exercises and the development of bilateral plans. It commands and supports United States Army assigned units, attached units, and augmentation forces and employs these forces in support of the commander. USARJ maintains and strengthens the credibility of deterrent power in the Pacific through maintenance of defense facilities, war reserves and operational project stocks. USARJ is headquartered at Camp Zama.

As the Army Component Command to United States Forces Japan (USFJ) and as a Major Subordinate Command of United States Army Pacific (USARPAC), United States Army Japan (USARJ)/I Corps (FWD) is responsible to provide support of Article V (Defense of Japan) and VI (ensuring regional stability) of the Mutual Security Treaty (MST). It serves as a forward stationed Army command and control headquarters; supports regional security cooperation activities with the Japan Ground Self Defense Force (JGSDF) for the purpose of contributing to the security of Japan and maintenance of peace and security in the Far East; provides communities of excellence and installation operations that support Soldiers, Civilians, and their Families.

United States Army, Japan consists of:
 * U.S. Army Garrison, Japan
 * 10th Support Group, Okinawa, Japan
 * U.S. Army Corps of Engineers, Japan District
 * U.S. Army Garrison, Japan, Band

History
Reorganization of U.S. forces in the Pacific in January 1953 established Army Forces Far East as the major Army command in the Far East. AFFE moved to Camp Zama, 35 miles southwest of Tokyo, in October 1953. On 20 November 1954, AFFE was combined with the Eighth US Army to become AFFE/Eighth US Army. In 1955, the Eighth US Army moved its headquarters to Yongsan Garrison, Seoul, Korea, and the Camp Zama command element was designated AFFE/Eighth US Army (Rear). The name, US Army Japan (USARJ), first appeared on 1 July 1957 in a reorganization of US forces in the Pacific.

A major change in the Army's command and organizational structure in the Pacific occurred on May 15, 1972, in conjunction with the return of Okinawa to Japanese control after twenty-seven years of administration by the United States. Under the complex reorganization that accompanied reversion, Headquarters, IX Corps, was transferred from Okinawa and collocated with Headquarters, U.S. Army, Japan, to form Headquarters, U.S. Army, Japan/IX Corps, at Camp Zama, Japan. On Okinawa, Headquarters, U.S. Army, Ryukyu Islands, and Headquarters, 2d Logistical Command, were inactivated and a U.S. Army Base Command, Okinawa, was established to command and support all Army units there and perform the theater logistic functions for United States and allied forces in the Pacific. Numerous other refinements were made to meet the dictates of operations in Southeast Asia and the gradual transition to peacetime conditions. Five subordinate commands were left within U.S. Army, Japan/ IX Corps, under the reorganization: the U.S. Army Base Command, Okinawa; the U.S. Army Supply and Maintenance Activity, Sagami; the U.S. Army Garrison, Kanto Plain; the U.S. Army Transportation Activity, Japan; the U.S. Army Ammunition Depot Complex, Akizuki; the U.S. Army Medical Activity, Japan; and the U.S. Army Procurement Agency, Japan. Total Army strength in Japan and Okinawa was reduced slightly as a result of this reorganization.

With the discontinuance of U.S. Army Pacific on December 31, 1974, U.S. Army Japan was designated a Major Army Command on January 1, 1975 reporting directly to Headquarters, Department of the Army. On February 28, 1971, the U.S. Army Hospital, Camp Kuwae, Okinawa was transferred to the Navy and concurrently U.S. Army Medical Department Activity, Japan, was disestablished, leaving USARJ with two subordinate commands, U.S. Army Garrison, Okinawa and U.S. Army Garrison, Honshu.

U.S. Army Garrison, Honshu, was re-designated the 9th Area Support Group (PROV) on January 16, 1986. The 9th Area Support Group terminated its provisional status on October 15, 1987, and was activated as the 17th Area Support Group. In line with the Department of the Army directed Transformation of Installation Management (TIM) initiative, U.S. Army Garrison, Japan was organized effective 16 Oct 2002 with the inactivation of the 17th Area Support Group and the merger of the installation management functions throughout Japan. USARJ's implementation of TIM also entailed the organization of the U.S. Army Host Nation Support Activity, Japan effective 1 October 2002 for consolidation of the Government of Japan funded Master Labor Contract (MLC) employees utilized by USARJ assigned units into a single mission career account.