The Decima Flottiglia MAS (Decima Flottiglia Mezzi d'Assalto, also known as La Decima or Xª MAS) (Italian for "10th Assault Vehicle Flotilla") was an Italian commando frogman unit of the Regia Marina (Italian Royal Navy) created during the Fascist regime. The acronym MAS also refers to various light torpedo boats used by the Regia Marina during World War I and World War II.