The first three units were constructed with a Terrier surface-to-air missile system. The supporting missile launchers and AN/SPG-55 radars consumed a large amount of space, while at the same time duplicating the capabilities of the air defence escorts, and were later removed. "John F. Kennedy" did not have Terrier and was built with the shorter ranged Sea Sparrow, Basic Point Defense Missile System (BPDMS). All were eventually equipped with NATO Sea Sparrow (NSSM) and Phalanx CIWS for self-defense. In 2001, "Kitty Hawk" received two Rolling Airframe Missile launchers replacing the forward Sea Sparrow and Phalanx CIWS equipment. The SLQ-32 Electronic Warfare Suite was added as part of the Service Life Extension Program (SLEP) on "Kitty Hawk" and "Constellation".