World War III

World War III (WW3). Also known as the Third World War. A hypothetical future global conflict subsequent to World War I (1914–1918) and World War II (1939–1945). It is widely assumed that such a war would involve all of the great powers, like its predecessors, as well as the use of nuclear weapons or other weapons of mass destruction, thus surpassing prior conflicts in geographic scope, devastation, and loss of life.

Since the Manhattan Project‘s development of nuclear weapons in 1945 and their use by the U.S. in the atomic bombings of Hiroshima and Nagasaki at the end of World War II, the risk of a nuclear apocalypse causing widespread destruction and the potential collapse of civilization or extinction of humanity has become a common theme in speculation and fiction about World War III.

With the advent of the Cold War (1947–1991) and spread of nuclear weapons to the Soviet Union, which was followed by their acquisition by several other countries, the risk of a third world war rose. During the Cold War, the possibility was anticipated and planned for by military and civil personnel around the world, with scenarios ranging from conventional warfare to limited or total nuclear warfare.

The strategic doctrine of mutually assured destruction, which posited that a full-scale nuclear confrontation would completely annihilate all parties to the conflict, was developed. U.S. and Soviet leaders worked to avoid such an outcome, though several close calls, caused by faulty technology, human error or miscommunication, still occurred, underscoring the need for restraint by both sides.

Various military conflicts which have occurred since the beginning of the 21st century, most notably the Russian invasion of Ukraine that has been ongoing since 2022, as well as rising geopolitical tensions between the U.S. and China including Taiwan and the South Seas, and the Israel-Hamas War have been perceived as potential flashpoints or triggers for a third world war.