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 states 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). 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 preparations that take place under the five DEFCONs are difficult to describe because they vary between many commands, they have changed over time as new weapon systems were deployed, and the precise details remain classified. Additionally, during tests, exercises, or drills, the United States Department of Defense uses exercise terms when referring to the DEFCONs. This is to preclude the possibility of confusing exercise commands with actual operational commands. The current exercise terms have been used since at least 1960, when they were used in a North American Air Defense Command (NORAD) exercise.
The five DEFCONs, their exercise terms, and their general descriptions are shown below.
Defense condition Exercise term Description Readiness
DEFCON 5 FADE OUT Lowest state of readiness Normal readiness
DEFCON 4 DOUBLE TAKE Increased intelligence watch and strengthened security measures
DEFCON 3 ROUND HOUSE Increase in force readiness above that required for normal readiness
DEFCON 2 FAST PACE Further increase in force readiness, but less than maximum readiness
DEFCON 1 COCKED PISTOL War is imminent. Maximum readiness