Hydrogen Bomb

It is a well known fact that during the Second World War, Nazi Germany was working towards developing a nuclear bomb which they could deploy over continents. Nearing the end of the war, the US managed to develop the atomic bomb first and they dropped two of them over Japan, therefor ending WW2. At the end of the war, both the US and the USSR rushed to their own development of thermonuclear weapons of mass destruction.

A hydrogen bomb going off (original and in color picture).

The key difference between an atomic and a hydrogen bomb is that the hydrogen bomb doesn't use fission but fusion. An H-bomb requires a small A-bomb to ignite in order to set off, while an A-bomb can be used as a weapon itself. In either case it is a very, VERY powerful weapon.