United States Navy maintains and trains naval forces for winning wars, deterring aggression and maintaining freedom of seas. It maintains a force of more than 331,400 personnel and a fleet of over 200 deployable battle force ships. The department has a fleet of battleships, submarines, frigates and cruisers. Its Naval Fleet Auxiliary Force includes ammunition, combat stores, dry cargo, rescue ships and fleet replenishment oilers. United States Navy maintains a fleet of special mission ships, including acoustic survey, missile range instrumentation and navigation test support. The department also has nearly 3,700 aircrafts. In addition, United States Navy has guns and weapon systems, as well as underwater search and recovery equipment.