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
Agathe (atomic test) "Vive La Bombe!". The French Defence Minister Pierre Messmer and other officials and civilians were present in the command post and were contaminated too (around >200 mSv). The millisievert (mSv) is commonly used to measure the effective dose in diagnostic medical procedures. See radiation poisoning for a more complete analysis of effects of various dosage levels. Data provided by the French Defense Ministry on January 2007. Agathe (atomic test) Agathe (aka Agate) was the name of the first French nuclear underground test. It was an atomic bomb detonated in the Hoggar mount (near In Ekker) of the then French Sahara