Phalanx CIWS: The Last Defense, On Ship and Ashore The radar-guided, rapid-firing MK 15 Phalanx Close-In Weapons System (CIWS, pron. “see-whiz”) can fire between 3,000-4,500 20mm cannon rounds per minute, either autonomously or under manual command, as a last-ditch defense against incoming missiles and other targets. Phalanx uses closed-loop spotting with advanced radar and computer technology to locate, identify and direct a stream of armor piercing projectiles toward the target. These capabil