<P> Nuclear weapons possess enormous destructive power from nuclear fission or combined fission and fusion reactions . Starting with scientific breakthroughs made during the 1930s , the United States , the United Kingdom and Canada collaborated during World War II in what was called the Manhattan Project to counter the suspected Nazi German atomic bomb project . In August 1945 , two fission bombs were dropped on Japan , standing to date as the only use of nuclear weapons in combat . The Soviet Union started development shortly thereafter with their own atomic bomb project , and not long after that both countries developed even more powerful fusion weapons known as `` hydrogen bombs '' . </P>
<P> Nuclear weapons possess enormous destructive power from nuclear fission or combined fission and fusion reactions . Starting with scientific breakthroughs made during the 1930s , the United States , the United Kingdom and Canada collaborated during World War II in what was called the Manhattan Project to counter the suspected Nazi German atomic bomb project . In August 1945 , two fission bombs were dropped on Japan , standing to date as the only use of nuclear weapons in combat . The Soviet Union started development shortly thereafter with their own atomic bomb project , and not long after that both countries developed even more powerful fusion weapons known as `` hydrogen bombs '' . </P>
where did the idea of the atomic bomb come from
where did the idea of the atomic bomb come from
Manhattan Project
Manhattan Project