1945 USA became the first country to develop and use a nuclear bomb, 1949 USSR had developed and tested its own nuclear bomb, 1953 Both countries had hydrogen bombs (thought USA bombs were still more powerful than the USSR's), 1955 the USSR developed and test a bomb called 'Sakharov's Third Idea' which was as powerful as America's hydrogen bombs, 1955 America developed the B52 Stratofortress with long range flight capacity, 1955 USSR was also in the process of developing the TU20 Bear