The Rolling Airframe Missile (RAM) MK-31 guided missile weapon system is co-developed and co-produced under a NATO cooperative program between the United States and German governments to provide a small, all-weather, low-cost self-defense system against aircraft and cruise missiles. The RIM-116 was later called RAM (Rolling Airframe Missile), because it spins during flight. To save costs, Designation Systems notes that the RAM was designed to use several existing components, including the rocket motor of the MIM-72 Chaparral, the warhead of the AIM-9 Sidewinder, and the Infrared seeker of the FIM-92 Stinger. Cueing is provided by the ship’s radar, or by its ESM signal tracing suite.
RAM is currently installed, or planned for installation, on 78 U.S. Navy and 30 German Navy ships, including American LSD, LHD, LPD and CVN ship types. This number will grow as vessels of the LPD-17 San Antonio Class and Littoral Combat Ships enter the US Navy, and the LCS will sport an upgraded SeaRAM system that will include its own integrated radar and IR sensors. Abroad, the South Korean Navy has adopted RAM for its KDX-II and KDX-III destroyers, and its LPX Dokdo Class amphibious assault ships; other navies using or buying RAM include Egypt, Greece, Japan, South Korea, Turkey, and the UAE/Dubai.