The Phalanx Close-In Weapons System (CIWS) was developed as the last line of automated weapons defense (terminal defense or point defense) against anti-ship missiles (AShMs or ASMs) and attacking aircraft, including high-g and maneuvering sea-skimmers.
The first prototype system was offered to the U.S. Navy for evaluation on the destroyer leader USS King in 1973 and it was determined that additional improvements were required to improve performance and reliability. Subsequently, the Phalanx Operational Suitability Model successfully completed its Operational Test and Evaluation (OT&E) on board the destroyer USS Bigelow in 1977. The model exceeded operational maintenance, reliability, and availability specifications. Another evaluation successfully followed, and the weapon system was approved for production in 1978. Phalanx production started with orders for 23 USN and 14 foreign military systems. The first ship fully fitted out was the aircraft carrier USS Coral Sea in 1980. The Navy began placing CIWS systems on non-combatant vessels in 1984.