The DEFCON system is a military readiness alert state used by the United States Armed Forces, established in 1959, with five levels ranging from DEFCON 5 (least severe) to DEFCON 1 (most severe), indicating an imminent nuclear war. Controlled by the U.S. president and defense officials, the DEFCON levels dictate specific readiness scenarios for military personnel, although the U.S. has never publicly declared DEFCON 1. The system is distinct from other military readiness measures and has been misrepresented in popular culture.