Meanwhile, negotiations continued with the Americans. Oliver Franks, the British Ambassador to the United States, lodged a formal request on 2 August 1951 for use of the Nevada Test Site. This was looked upon favourably by the United States Secretary of State, Dean Acheson, and the chairman of the United States Atomic Energy Commission, Gordon Dean, but opposed by the Robert A. Lovett, the American Deputy Secretary of Defense and Robert LeBaron, the Deputy Secretary of Defence for Atomic Energy Affairs. The British government had announced on 7 June 1951 that Donald Maclean, who had served as a British member of the Combined Policy Committee from January 1947 to August 1948, had been a Soviet spy. In view of security concerns, Lovett and LeBaron wanted the tests to be conducted by Americans, British participation being limited to Penney and a few selected British scientists. Truman endorsed this counterproposal on 24 September 1951.