Intercepting Warheads
As the very first action of a post, even before taking any damage, a ship has the opportunity to shoot down incoming warheads. These are warheads that are targeting the ship itself. Any weapons used to shoot down warheads cannot be used again to attack another target but shooting down warheads does not count as one of your unit's attacks either.
Due to the high velocity of warheads, shooting them down is not easily accomplished. To determine the success rate consult the table below.
Missile - 4 Laser Cannons / 4 Missiles
Torpedo - 2 Laser Cannons / 2 Missiles
This table reads as such: you must fire 4 Laser Cannons at an incoming Missile to intercept it and avoid the possible damage.
Combat Air/Space Patrol
Starfighters on CAP/CSP for a unit may also intercept warheads for a unit, though this action counts as making an attack for the starfighters. They would be considered engaged (no longer on CSP) and also unable to fire the weapons used to target warheads again in the same post.