DEFCON (Defense Condition)
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).
Defense readiness conditions (DEFCONs) describe progressive alert postures primarily
for use between the Joint Chiefs of Staff and the commanders of unified commands.
DEFCONs are graduated to match situations of varying military severity, and are numbered 5,4,3,2, and 1 as appropriate.
DEFCONs are phased increases in combat readiness. In general terms, these are descriptions of DEFCONs:
DEFCON 5 - Normal peacetime readiness
DEFCON 4 - Increased intelligence & strengthened security
DEFCON 3 - Increase in force readiness above normal
DEFCON 2 - Further Increase in force readiness
DEFCON 1 - Maximum force readiness.

We are now at DefCon level: 4