At this Readiness level, personell on leave are recalled,SAC
or Strategic Air Command
would, in bygone days, have B52
s on the tarmac, fuelled, and be ready to fly at short notice.
These would be eqqiupped with ICBMs (Inter Continental Ballistic Missiles) and or SRAMs (Short Range Attack Missiles) which would both contain Nuclear Weapons, or possibly other Weapons Of Mass Destruction.