The domino theory said that if one country fell to communism, its surrounding countries would be threatened by communist expansion. The theory was introduced by Eisenhower
The domino theory relied on an idea about how ideologies spread throughout different regions. According to this theory, if one country became communist, this would have an impact on the neighbouring countries, which would lead to them also becoming communist. This idea was essential to the Cold War, as it provided a justification for the determination of the United States in eliminating all threats of communism.
