The United States Forces Japan (USFJ) is a subordinate unified command of the United States Indo-Pacific Command. It was activated at Fuchū Air Station in Tokyo, Japan, on 1 July 1957 to replace the Far East Command. USFJ is headquartered at Yokota Air Base in Tokyo and is commanded by the Commander, US Forces Japan who is also commander of the Fifth Air Force.

A unified combatant command, also referred to as a combatant command (CCMD), is a joint military command of the United States Department of Defense that is composed of units from two or more service branches of the United States Armed Forces, and conducts broad and continuing missions. There are currently 11 unified combatant commands, and each is established as the highest echelon of military commands, in order to provide effective command and control of all U.S. military forces, regardless of branch of service, during peace or during war time. Unified combatant commands are organized either on a geographical basis or on a functional basis, e.g., special operations, force projection, transport, and cybersecurity. Currently, seven combatant commands are designated as geographical, and four are designated as functional. Unified combatant commands are "joint" commands and have specific badges denoting their affiliation.