United States Space Command
Formerly the center for the United States Space Command and NORAD, the Complex monitored the air space of Canada and the United States for missiles, space systems, and foreign aircraft through its worldwide early-warning system. Since 2008, NORAD and the United States Space Command have been based at Peterson Space Force Base and the complex, re-designated as an air force station, is used for crew training and as a back-up command center if required.