1958 US–UK Mutual Defence Agreement as an atomic spy, caused the proposal to be dropped. The June 1951 defection of Donald Maclean, who had served as a British member of the Combined Policy Committee from January 1947 to August 1948, reinforced the Americans' distrust of British security arrangements. The first British atomic bomb was successfully tested in Operation Hurricane on 3 October 1952, but although it was more advanced than the American bombs of 1946, Britain was still several years behind in nuclear weapons technology. The United States conducted Ivy Mike, the first nuclear test of a true thermonuclear device (also known as a hydrogen
Atomic demolition munition and all were removed from stockpile by 1966. A weapons effect test of the TADM was made in the 1962 Johnny Boy ("Johnnie Boy") shot of the Dominic II series (which is more accurately referred to as Operation Sunbeam), the yield of Johnny Boy/Johnnie Boy was about .5 kt. A preceding ADM test which resulted in a comparable yield, was test shot "Danny Boy" of Operation Nougat, also producing a yield of about 0.5 kiloton. The "Special Atomic Demolition Munition (SADM)" was a family of man-portable nuclear weapons fielded by the US military in the 1960s, but never used in