During the initial involvement of the USAF Security Police units in the Vietnam insurgency, internal security of remote and vulnerable air bases continued to be carried out under the long existing concept of providing internal protection against the covert threat of sabotage.

Well planned attacks by organized guerilla raiding parties on three of the major air bases in Vietnam forced the USAF to redirect its attention from internal security to providing a well trained and well armed, highly motivated combat security police force capable of repelling raids by experienced enemy sapper units.

A security survey was conducted by the USAF Inspector General in the Republic of Vietnam in 1965 and presented to the Chief of Staff, USAF with the recommendation that a test unit of highly trained Combat Security Police be formed to initiate a new concept, known as "Active Defense."