Phalanx 20mm gun. Accept no substitutes.
I remember being in during the eighties. The CIWS Phalanx 20mm guns then had no electro-optical (TV) sighting system and were useless for shooting surface targets or basically anything that wasn’t an approaching missile.
During Beiruit, this led to the pathetic spectacle of USN cruisers and destroyers requiring marine sharpshooters and stinger missile wielders on deck to protect the ships from attacks by small airplanes and motorboats.
It was a ludicrous spectacle.