Nuclear weapon

A nuclear weapon, nuclear bomb or a nuke, is a weapon that suddenly releases the energy in the nucleus of certain types of atoms. When triggered, the device releases a huge amount of energy in the form of a nuclear explosion.

Nuclear explosions can destroy a city and kill most of its people. They also make nuclear fallout. This radioactive material can make people ill. Nuclear weapons are the most damaging weapons mankind has created.

The first nuclear weapons were built by the United States during World War II. Two nuclear weapons were used to attack cities in Japan. They were the only times nuclear weapons were used in war.

There are two types of nuclear weapons: fission weapons (also called atomic bombs or A-Bombs) and fusion weapons (also called hydrogen bombs, H-Bombs, or thermonuclear weapons). They make energy for the nuclear explosion in different ways. Fusion weapons make bigger explosions. Fission weapons use a special isotope of uranium or plutonium. Fusion weapons use a special isotope of hydrogen. Nuclear weapons have been used twice in war, both by the United States in the atomic bombings of Hiroshima and Nagasaki in 1945.

Since the atomic bombings of Hiroshima and Nagasaki, nuclear weapons have been detonated over 2,000 times for testing and demonstration. Only a few nations possess such weapons or are suspected of seeking them. The only countries known to have detonated nuclear weapons and to say they have them are (in order from the first time the country had tested them) the United States, the Soviet Union (succeeded as a nuclear power by Russia), the United Kingdom, France, China, India, Pakistan, and North Korea. Israel is believed to have nuclear weapons, but in a policy of deliberate ambiguity, does not say so. Germany, Italy, Turkey, Belgium and the Netherlands share nuclear weapons with other countries. South Africa is the only country that has independently developed and later renounced and dismantled its nuclear weapons.

The Treaty on the Non-Proliferation of Nuclear Weapons aims to reduce the spread of nuclear weapons. Its effectiveness has been questioned.