United States Army, Japan (USARJ) is a Major Command of the United States Army. It consists of 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.

Camp Zama (キャンプ座間) is a United States Army post located in the cities of Zama and Sagamihara, in Kanagawa Prefecture, Japan, about 40 km (25 mi) southwest of Tokyo.