In the event of a
national emergency, a series of seven different
alert Conditions (LERTCONs) can be called. The 7 LERTCONs are broken down into 5
Defense Conditions (
DEFCONs) and 2 Emergency Conditions (
EMERGCONs).
The furthest we have ever gotten to on the LERTCON ladder is
DEFCON 2, during the cuban missile crisis in 1965.