Although the plan was to build all-British nuclear submarines, much time would be saved by accepting American nuclear technology. The excellent relations between Admiral Mountbatten and US Navy Chief of Naval Operations Arleigh Burke, expedited obtaining that help. This was despite Rear Admiral Hyman Rickover, in charge of the American naval nuclear power programme, being set against any transfer of technology; indeed, Rickover prevented Mountbatten inspecting USS "Nautilus". It was not until a visit to Britain in 1956 that Rickover changed his mind and withdrew his objections. Although Rickover wished to supply the third generation S3W reactor of the , Mountbatten exerted his influence and the entire machinery system for an American , with its fifth generation S5W reactor, was obtained. This was known as the "American Sector" (see 1958 US-UK Mutual Defence Agreement). The hull and combat systems of "Dreadnought" were of British design and construction, although British access to the Electric Boat Company influenced the hull form and construction practices.