Defcon

DEFCON is the "defense readiness condition," which is state of alertness to military conflict as determined from time to time by the United States Armed Forces.

There are five levels; the lower the number, the higher the state of alertness:

• DEFCON 5 -- normal readiness, this is the lowest state
• DEFCON 4 -- above normal state of readiness, intelligence watch and security measures are increased
• DEFCON 3 -- an increase in readiness above normal, the Air Force is ready to mobilize in 15 minutes if required
• DEFCON 2 -- next step to nuclear war, the Armed Forces are ready to deploy and engage in six hours
• DEFCON 1 -- maximum readiness/immediate response, nuclear war is imminent or has already begun

There is no worldwide or country-specific DEFCON status: it can and has been declared to include only specific geographical areas. Worldwide the level has never been declared above DEFCON 3.

DEFCON 1 has never been declared in United States history.

DEFCON 3 has been declared only three times: after the Yom Kippur War, in South Korea in 1976 after an axe murder in the Korean DMZ, and after the September 11 attacks. DEFCON 2 has been declared only twice: during the Cuban Missile Crisis and the opening phase of the Persian Gulf War.