Eight
Eight different nations around the world have successfully detonated nuclear weapons. Five of these eight countries are designated as states that reserve the right to have nuclear weapons on their grounds, which was decided upon in the Treaty on the Non-Proliferation of Nuclear Weapons.

The United States conducted 1,032 nuclear tests between 1945 and 1992: at the Nevada Test Site, at sites in the Pacific Ocean, in Amchitka Island of the Alaska Peninsula, Colorado, Mississippi, and New Mexico.

Nuclear weapons have been tested in all environments since 1945: in the atmosphere, underground and underwater. Tests have been carried out onboard barges, on top of towers, suspended from balloons, on the Earth’s surface, more than 600 metres underwater and over 200 metres underground.

The United States conducted most of its tests at a dedicated site in Nevada until 1992, and also in the Marshall Islands in the Pacific Ocean.

Australia does not possess any nuclear weapons and is not seeking to become a nuclear weapons state. Australia’s core obligations as a non-nuclear weapon state are set out in the NPT.

Canada is generally considered to be the first nation to have voluntarily given up its nuclear weapons. Systems were deactivated beginning in 1968 and continuing until 1984. (See Disarmament.) Canada maintains the technological capability to develop nuclear weapons.

The United States has not conducted a nuclear test explosion since September 1992, and nuclear nonproliferation advocates warned that doing so now could have destabilizing consequences. Still, the major nuclear powers abide by its core prohibition on testing.

Most damage comes from the explosive blast. When a nuclear weapon is detonated on or near Earth’s surface, the blast digs out a large crater. Some of the material that used in be in the crater is deposited on the rim of the crater; the rest is carried up into the air and returns to Earth as radioactive fallout.

If a nuclear weapon is exploded in a vacuum-i. e., in space-the complexion of weapon effects changes drastically: First, in the absence of an atmosphere, blast disappears completely. There is no longer any air for the blast wave to heat and much higher frequency radiation is emitted from the weapon itself.

North Korea has a military nuclear weapons program and, as of early 2020, is estimated to have an arsenal of approximately 30 to 40 nuclear weapons and sufficient production of fissile material for six to seven nuclear weapons per year.

In accordance with Article 2 of the treaty, New Zealand submitted a declaration to the UN secretary-general on 18 January 2021 confirming that it does not own, possess, or control nuclear weapons, has never done so, and does not host any other state’s nuclear weapons on its territory.

OCTOBER 1962–AMERICA AND THE SOVIET UNION, FACE OFF IN THE WATERS BETWEEN FLORIDA AND CUBA. Man: EVERYBODY’S GOT A NUKE IN THEIR POCKET. ONE SPARK WOULD SET IT OFF. Announcer: 50 YEARS LATER, THE STUNNING REVELATION THAT THE WORLD WAS CLOSER TO NUCLEAR DESTRUCTION THAN WE KNEW.