The domino theory was an important component of the U.S. Cold War geopolitical model of the world, which divided the world into three parts: the First World (the West), the Second World (communist states), and the Third World (colonies and newly independent states). Proponents of the domino theory argued that the loss of one [Page 787]country in the First or Third World to communist control would trigger the loss of its neighboring countries to communism.

While the origins of the concept have been traced to early in the 20th century, the domino theory emerged in full force in U.S. foreign policy circles in the aftermath of World War II. The concept was advanced in 1947 both by the former U.S. ambassador to the Soviet Union, William ...