While numerous warships and submarines were built with nuclear marine propulsion, attempts to utilize the nearly unlimited range provided by an onboard nuclear reactor to transport commercial cargo were limited to a small number of experimental prototypes. The United States had built the world's first nuclear-powered merchant ship, "Savannah", primarily as a technological demonstrator and ambassador for the peaceful use of atomic power rather than an economically viable cargo ship. Similarly, both the West German "Otto Hahn" and the Japanese "Mutsu" were intended to be research ships and to provide experience from nuclear propulsion; the latter also never carried any commercial cargo.