Domino theory

The domino theory was a theory prominent from the 1950s to the 1980s, that speculated that if one country in a region came under the influence of communism, then the surrounding countries would follow in a domino effect. The domino theory was used by successive United States administrations during the Cold War to justify the need for American intervention around the world.

Though he never used the precise term "domino theory", U.S. President Dwight D. Eisenhower described the theory during an April 7, 1954, news conference, when referring to communism in Indochina:

Finally, you have broader considerations that might follow what you would call the "falling domino" principle. You have a row of dominoes set up, you knock over the first one, and what will happen to the last one is the certainty that it will go over very quickly. So you could have a beginning of a disintegration that would have the most profound influences.

In 1945, the Soviet Union brought most of the countries of eastern Europe and Central Europe into its influence as part of the post-World War II new settlement, prompting Winston Churchill to declare in a speech in 1946 at Westminster College in Fulton, Missouri that:

Following the Iran crisis of 1946, Harry S. Truman declared what became known as the Truman Doctrine in 1947, promising to contribute financial aid to Greece during their Civil War and to Turkey following World War II, in the hope that this would impede the advancement of Communism into Western Europe. Later that year, diplomat George Kennan wrote an article in Foreign Affairs magazine that became known as the "X Article", which first articulated the policy of containment, arguing that the further spread of Communism to countries outside a "buffer zone" around the USSR, even if it happened via democratic elections, was unacceptable and a threat to U.S. national security. Kennan was also involved, along with others in the Truman administration, in creating the Marshall Plan, which also began in 1947, to give aid to the countries of Western Europe (along with Greece and Turkey), in large part with the hope of keeping them from falling under Soviet domination.

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