domino theory

Domino theory presents a metaphor of falling dominoes: that a rise or fall in communist influence in a country will have the same knock-on effect in neighboring countries, and so on.

The domino theory is a geopolitical theory which posits that changes in the political structure of one country tend to spread to neighboring countries in a domino effect. It was prominent in the United States from the 1950s to the 1980s in the context of the Cold War, suggesting that if one country in a region came under the influence of communism, then the surrounding countries would follow. It was used by successive United States administrations during the Cold War as justification for American intervention around the world. U.S. President Dwight D. Eisenhower described the theory during a news conference on April 7, 1954, when referring to communism in Indochina as follows: