sentences:  , , and were equipped with the Block 0 version of the Phalanx, while received the first operational Block 1 version in 1988.Developed as the final line of defense (terminal defense or point defense) against anti-ship missiles, the Phalanx Close in Weapon System (CIWS, pronounced ""sea-whiz"") is the anti-aircraft/anti-missile gun currently in use in the US Navy.Due to their distinctive shape, they have been nicknamed "R2D2s", in reference to the droid R2-D2 from the Star Wars universe.