A Minuteman Mobility Test Train was a Cold War train for Strategic Air Command testing before deployment of planned trains for launching Minuteman missiles which were to allow periodic movement for security from targeting by the Soviet missile force. At the time, the trains had the heaviest railroad cars used on regular rail routes, and rail sidings were surveyed during the trains' 1960 Operation Big Star (surveyed sites were subsequently used in 1961 by different SAC trains for evaluating bomber accuracy.)