The Skywarrior could carry up to of weaponry in the fuselage bomb bay, which in later versions was used for sensor and camera equipment or additional fuel tanks. An AN/ASB-1A bomb-director system was initially installed, later replaced by a revised AN/ASB-7 with a slightly reshaped nose. Defensive armament was two 20mm cannons in a radar-operated tail turret designed by Westinghouse, soon removed in favor of electronic counter measure equipment. Although some bombing missions would be carried out early in the Vietnam War, most bombing would be carried out by more nimble attack and fighter bombers, and the Skywarrior would serve mostly as a tanker and electronic warfare support aircraft.