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.

Japan was occupied and administered by the Allies of World War II from the surrender of the Empire of Japan on September 2, 1945, at the war's end until the Treaty of San Francisco took effect on April 28, 1952. The occupation, led by the American military with support from the British Commonwealth and under the supervision of the Far Eastern Commission, involved a total of nearly one million Allied soldiers. The occupation was overseen by the US General Douglas MacArthur, who was appointed Supreme Commander for the Allied Powers by the US President Harry S. Truman; MacArthur was succeeded as supreme commander by General Matthew Ridgway in 1951. Unlike in the occupations of Germany and Austria, the Soviet Union had little to no influence in Japan, declining to participate because it did not want to place Soviet troops under MacArthur's direct command. And unlike Germany, the Japanese government still remained in place throughout the occupation.