However, the nuclear submarine propulsion effort was running into trouble. Under the July 1956 agreement and a February 1957 directive from Eisenhower, Royal Navy officers had been assigned to study the US Navy's nuclear submarine programme. By October 1957, its head, Rear Admiral Hyman G. Rickover, felt that their questions were slowing the deployment of the Polaris submarine-launched IRBM at a critical time. He feared that any delay might cause Congress to favour land-based missiles. By December, the British liaison officers were complaining of slow response to their questions. Rickover proposed that Westinghouse be permitted to sell the Royal Navy a nuclear submarine reactor, which would allow it to immediately proceed with building its own nuclear-powered submarine. The British government endorsed this idea, as it would save it a great deal of money.