What is a defcon countdown?

Defcon 2 is NOT the order to launch. Defcon (1 thru 5) are degrees of readiness.

From Answers.com:

The defense readiness condition (DEFCON) is a measure of the activation and readiness level of the United States Armed Forces. It describes progressive postures for use between the Joint Chiefs of Staff and the commanders of unified commands. DEFCONs are matched to the situations of military severity. Standard peacetime protocol is DEFCON 5, descending in increasingly severe situations. DEFCON 1 represents expectation of actual imminent attack, and it has never been declared, except perhaps partially during the Gulf War in 1991.

In a national state of emergency, seven different alert conditions known as LERTCONs can be issued. They consist of five Defense Conditions and two Emergency Conditions (EMERGCONs).

Levels DEFCON 5
This is the condition used to designate normal peacetime military readiness. An upgrade in military preparedness is typically made by the Joint Chiefs of Staff and announced by the United States Secretary of Defense. DEFCON 4
This refers to normal, increased intelligence and the heightening of national security measures. Readiness remained at this level throughout most of the Cold War. DEFCON 3
This refers to an increase to force readiness above normal. Radio call signs used by American forces change to currently-classified call signs. DEFCON 2
This refers to a further increase in force readiness just below maximum readiness. It has been declared only once, during the Cuban Missile Crisis. DEFCON 1
This refers to maximum readiness. It is not certain whether this has ever been used, but it is reserved for imminent or ongoing attack on US military forces or US territory by a foreign military power. Use of nuclear missiles is authorized.

History

Cold War See also: Cold War The highest alert condition the US military has been confirmed to have been at was DEFCON 2. During the Cuban Missile Crisis on 22 October 1962, Strategic Air Command (SAC) was ordered to 2 and the rest of the US military to 3. SAC remained at 2 until 15 November.

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