Franklin D. Roosevelt started the development of an explosive device that derives its destructive force from nuclear reactions.
As an active military leader , Roosevelt implemented a war strategy on two fronts that ended in the defeat of the Axis Powers , and he initiated the development of the world 's first atomic bomb .	Axis Powers	Axis Powers	atomic bomb	nuclear bomb
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions , either fission -LRB- fission bomb -RRB- or a combination of fission and fusion -LRB- thermonuclear weapon -RRB- .	fission	nuclear fission	fission bomb	fission bomb	fusion	nuclear fusion	thermonuclear weapon	thermonuclear weapon
