nuclear weapon ( also called an atom bomb , nuke , atomic bomb , nuclear warhead , A-bomb , or nuclear bomb ) is an explosive device that derives its destructive force from nuclear reactions , either fission ( fission bomb ) or from a combination of fission and fusion reactions ( thermonuclear bomb ) . Both bomb types release large quantities of energy from relatively small amounts of matter . The first test of a fission ( " atomic " ) bomb released an amount of energy approximately equal to . The first thermonuclear ( " hydrogen " ) bomb test released energy approximately equal to . A thermonuclear weapon weighing little more than can release energy equal to more than . A nuclear device no larger than traditional bombs can devastate an entire city by blast , fire , and radiation . Since they are weapons of mass destruction , the proliferation of nuclear weapons is a focus of international relations policy
first test
Trinity (nuclear test)
Nuclear weapon