The effects of an underground nuclear test can vary greatly depending on the depth and power of the explosion, as well as the nature of the surrounding rock. If the test is conducted at a deep enough level, it is said to be contained, without releasing any gases or other contaminants into the environment. The preamble of the treaty banning nuclear weapons acknowledges the disproportionate impact of nuclear weapons activities on indigenous peoples. The International Campaign to Abolish Nuclear Weapons (ICAN) is a coalition of non-governmental organizations from one hundred countries that are committed to adhering to and implementing the United Nations Treaty on the Prohibition of Nuclear Weapons. These monitors were initially designed to detect radionuclides that were released after a nuclear weapon was detonated.
Some studies and evaluations, including an evaluation by Arjun Makhijani of the health effects of nuclear weapons complexes, estimate that cancer deaths due to global radiation doses from nuclear test programs in the atmosphere of the five nuclear-weapon States amount to hundreds of thousands. Whenever North Korea carries out an underground nuclear test, a wide range of global sensors will detect it almost immediately. The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a legally binding global ban on testing nuclear explosives. Recognizing that even underground tests can cause serious damage, and wanting to end the era of nuclear testing, the international community adopted the Comprehensive Nuclear-Test-Ban Treaty in 1996. According to the CTBTO, out of more than 2,000 nuclear detonations since 1945, 75% have been tests conducted underground, mainly by the major nuclear powers such as the United States, Russia (formerly the Soviet Union), Great Britain, France and China.
