Nuclear Weapon is the destructive force

A nuclear weapon is a volatile tool that derives its destructive force from nuclear reactions, either fission or a mixture of fission and fusion. Both reactions discharge vast amounts of energy from moderately small amounts of matter; a modern thermonuclear weapon weighing little more than a thousand kilograms can manufacture an explosion similar to the explosion of more than a billion kilograms of conservative high explosive. Even small nuclear devices can destroy a city. Nuclear weapons are measured weapons of mass destruction, and their use and control has been a major aspect of worldwide policy since their debut.
Since the Hiroshima and Nagasaki bombings, nuclear weapons have been exploded on over two thousand occasions for testing purposes and revelation purposes. The only countries known to have detonated nuclear weapons – and that acknowledge possessing such weapons – are (chronologically) the United States, the Soviet Union (succeeded as a nuclear power by Russia), the United Kingdom, France, the People's Republic of China, India, Pakistan, and North Korea. Israel is also widely supposed to possess nuclear weapons, though it does not acknowledge having them. For more information on these states' nuclear programs, as well as other states that formerly possessed nuclear weapons or are suspected of seeking nuclear weapons, see List of states with nuclear weapons.