Defcon 5 Edit
Defcon 4 Edit
Defcon 3 Edit
Launch some fighters into neighboring territories to scout. You can find some of their units there. Easy targets. One word of warning though, send out your fighters in waves, to stop them getting picked off easily by Enemy defenses.
Defcon 2 Edit
Get your bombers airborne as Defcon 1 approaches - they can be switched while in mid-air to SRBM mode and this will render them less vulnerable to a surprise attack.
Defcon 1 Edit
The safest method for Defcon 1 is to wait for someone else to strike. If their country is neighbouring yours, launch bombers first to take out silos that are currently firing ICBMs- this will cut them short in the attack, but also prevent them from taking down your own aircraft. Be sure to send fighters to escort your bombers, as they may be attacked by enemy fighters.
When the enemy has been prevented from using ICBMs, prepare a counter-attack and aim for their other tactical radar positions, as this will again cut off their field of vision, thus making them more susceptible to the forthcoming ICBM attacks.
When all known enemy radar and silos are destroyed, launch several ICBMs from silos that are not near your cities towards enemy capitals. By doing so, this will leave some anti-aircraft defense near your cities, which will be the ones to shoot down other missiles, posssibly from bombers or submarine attacks.
Finally, when most, if not all fighting has stopped and your enemy has no defense left, you may use your own submarines to finish off any surviving populations in enemy territory.