Belleville AFS was one of twenty-eight stations built as part of the second segment of the Air Defense Command permanent radar network, primarily to provide air defense radar coverage for Saint Louis and Scott Air Force Base. Prompted by the start of the Korean War, on July 11, 1950, the Secretary of the Air Force asked the Secretary of Defense for approval to expedite construction of the permanent network. Receiving the Defense Secretary’s approval on July 21, the Air Force directed the Corps of Engineers to proceed with construction.