1955    November 22- First fusion device test by the Soviet Union, it had a yield of 
	1.6 megatons. The development was lead by Andrei Sakharov. 

1957    May 15-First British H-bomb exploded at Christmas Island.
	September 19-First underground test, Rainier, 1.7 kilotons. 

1958    November, 1958 to September, 1961-U.S., U.K., and U.S.S.R. observe an 
	informal moratorium on nuclear tests.