Anti-Air defences are key to protection against helicopters. These prefer to fire at air units, but can damage both air and ground units. Upgrade these to missile batteries once you have donated enough to Alliance.
|Level 1||Level 2||Level 3|
|Level 4||Level 5||Level 6|
|Damage ratio vs vehicles||100%|
|Damage ratio vs aircrafts||300%|
|Damage ratio vs infantry||50%|
|Level||Hit Points||Damage per Second||Range|