DEFCON 1 is the threat level at which Nuclear Missiles can be fired, they can be ICBMs, MRBMs or SRBMs.

It is generally at that stage that the most intense diplomatic tractations ensues. It is generally the longest stage of the game as no player will want to be the first to attack, as it leaves them wide open for an attack.

More information on DEFCON 1 tactics and gameplay can be found on unit, structure, regions, and other various pages throughout this Wiki.