What concept refers to the fear that if one nation falls to communism, its neighbors will follow?

The concept that refers to the fear that if one nation falls to communism, its neighbors will follow is known as the "Domino effect." This term was popularized during the Cold War, particularly in the context of U.S. foreign policy regarding the spread of communism. The idea is that the fall of one country to communism would lead to a chain reaction, causing neighboring countries to also succumb to communist influence or governance, akin to a line of dominos toppling over one after another.

Understanding this concept is crucial in analyzing the motivations behind various international policies during the Cold War, such as the U.S. approach to conflicts in Southeast Asia. The notion of the "Domino effect" significantly influenced decisions such as the escalation of military involvement in Vietnam, as American leaders sought to prevent what they perceived to be the inevitable spread of communism in the region if Vietnam fell.

While the other terms might seem comparable, they do not specifically capture the nature of this fear about communism's spread. The "Chain reaction" implies a similar progression but lacks the specific ideological context associated with the domino analogy. The "Contagion effect" suggests a spread of ideas or behaviors but does not clearly convey the geopolitical implications of communism as does