Homeland security and civil defence plansįEMA-estimated primary counterforce targets for Soviet ICBMs.
One of the first imagined scenarios, hypothesized shortly after or even during World War II, is a nuclear war between the United States and the Soviet Union, which emerged as superpowers following World War II. Another major concern is that biological warfare could cause a very large number of casualties, either intentionally or inadvertently by an accidental release of a biological agent or the unexpected mutation of an agent or its adaptation to other species after use. A common hypothesis is that a small number of people could survive such an armageddon, possibly in deep underground blast shelters or away from Earth such as on the Moon or Mars or in space vehicles. Because of the development and use of nuclear weapons near the end of World War II and their subsequent acquisition and deployment by several countries, it is feared that a third world war could cause massive global destruction and could even cause the end of and most or all human life on Earth. World War III ( WWIII, WW3 or the Third World War) is a hypothetical worldwide military conflict following World War II. For other uses, see World War III (disambiguation).