A defense readiness condition (
DEFCON) is an alert posture used by the
United States armed forces. The DEFCON
system was developed by the Joint Chiefs of Staff and unified and specified combatant commands. It prescribes five graduated levels of readiness (or statuses of alert) for the U.S. military, and increase in severity from DEFCON 5 (least severe) to DEFCON 1 (most severe) to match varying military situations.
DEFCONS are a subsystem of a series of Alert Conditions, or LERTCONs, that also includes Emergency Conditions (EMERGCONs).3 DEFCONs should not be confused with similar systems used by the U.S. military, such as
Force Protection Conditions (FPCONS) and Watch Conditions (WATCHCONS), or the Homeland Security Advisory
System used by the United States Department of Homeland Security. The highest confirmed
DEFCON ever was Level 2 (DEFCON2). Movies and popular culture often misuse the DEFCON
system by "going to DEFCON 5" during a state of emergency. In fact, DEFCON 5 is the lowest state of readiness. DEFCON 1 is the most severe.