Fast combat support ship  The fast combat support ship (US Navy hull classification symbol: AOE) is the United States Navy's largest combat logistics ship, designed as an oiler, ammunition and supply ship. All fast combat support ships currently in service are operated by Military Sealift Command. They can carry more than 177,000 barrels of oil, 2,150 tons of ammunition, 500 tons of dry stores and 250 tons of refrigerated stores. It receives petroleum products, ammunition and stores from various shuttle ships and redistributes these items when needed to ships in the carrier battle group. This greatly reduces the number of service ships needed to travel with carrier battle groups. The four ships of the were 53,000 tons at full load, 796 feet overall length, and carried two Boeing Vertol CH-46 Sea Knight helicopters. The "Sacramento" class was retired in 2005. The ships displace 48,800 tons full load and carried two Boeing Vertol CH-46 Sea Knight helicopters or two Sikorsky MH-60S Knighthawk helicopters. Air defense includes the Sea Sparrow radar and infrared surface-to-air missile in eight-cell launchers to provide point defence with 15km to 25km range. There are also two Phalanx mk15 20mm gatling gun close-in weapon systems (CIWS) and two 25mm Raytheon mk88 guns. China has developed the Type 901 fast combat support ship which serves a similar mission in their navy.