In late 1951 Air Defense Command selected Opheim, Montana as one of twenty-eight radar stations built as part of the second segment of the permanent radar surveillance network. 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 second segment 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. In addition to the main facility, Opheim operated two AN/FPS-14 Gap Filler sites: