The Defense Attaché Office, Saigon was a joint-service command and military attaché branch of the United States Department of Defense (DOD) under the control of United States Support Activities Group (USSAG). It assumed all DOD responsibilities in South Vietnam following the disestablishment of Military Assistance Command, Vietnam (MACV) in March 1973. The DAO was responsible for administering military assistance and support to the South Vietnamese armed forces, the gathering and distribution of military intelligence and the performance of normal Defense Attaché functions. The DAO remained in existence until August 1975.

Tan Son Nhut Air Base (1955–1975) was a Republic of Vietnam Air Force (RVNAF) facility. It was located near the city of Saigon in southern Vietnam. The United States used it as a major base during the Vietnam War (1959–1975), stationing Army, Air Force, Navy, and Marine units there. Following the Fall of Saigon, it was taken over as a Vietnam People's Air Force (VPAF) facility and remains in use today.