My old ID - DEFCON

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 partially during the Gulf War.

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. During the Cuban Missile Crisis, one of the specific conditions of escalating to level 4 prompted the military to replace training (or "dummy") tips with live nuclear warheads on all target selected ICBMs.

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 only been declared 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 weapons is authorized. (State of Emergency.)