In combat involving planes, the AD units are the first pieces to fire at the beginning of each round of battle. The defender rolls one die for each AD unit per attacking plane. For example if a territory is defended with two AD units and four planes attack, the defender would roll 8 dice. Any roll of '1' strikes a hit. The attacker removes any casualties immediately without a chance of firing. Any paratroopers being carried are killed before having a chance to jump. The battle would then continue like normal. This procedure is repeated for each round of battle.

AD units have a movement value of 1 or can be transported by transport ship or aircraft carrier and do not take up any cargo space. When on a transport or carrier, they help defend against enemy air strikes. No more than 2 AD units can be active on any single territory.

If a country has more than 2 units, only 2 will defend against the planes or nukes. AD units can be purchased at the same time as new complexes and placed on the board together. Also, newly purchased guns can be placed on any territory containing a complex. Even one just captured in the same turn.

AD units only fire when they are attacked directly. Planes are free to fly over enemy AD units without facing attacks.