The domino theory was critical in shaping US foreign policy during the Cold War. Domino theory argued that if one nation became communist, its neighboring states would go the same way. In theory, if one state “fell” to communism, its neighbors would also fall, setting off a chain reaction comparable to a line of toppling dominoes.
The drive to contain communism was a major influence on the Truman administration, motivating the government to start providing aid to the French government in Indochina. Truman also assisted Greece and Turkey in the late 1940s in an effort to contain the spread of communism.
However, it was President Eisenhower who really popularized the concept of domino theory. At a press conference in April, 1954, a reporter asked Eisenhower about his opinion on Indochina and its strategic importance. Eisenhower replied, in part:
You have, of course, both the specific and the general when you talk about such things. First of all, you have the specific value of a locality in its production of materials that the world needs. Then you have the possibility that many human beings pass under a dictatorship that is inimical to the free world.
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.
Eisenhower returned to this concept repeatedly, in speeches about the “aggressive” nature of communism and the need to contain its spread. The Eisenhower administration also used domino theory to explain why the US was intervening in Indochina but not, for example, in Franco’s Spain. The National Security Council agreed that it did not want to “police the governments of the entire world” – it did, however, want to fight communism and beat out Moscow.
Domino theory was closely linked to US presence in Vietnam. Both the Kennedy and the Johnson administrations used domino theory to justify escalating the American military presence in Vietnam. Henry Kissinger, the Secretary of State under Presidents Nixon and Ford, was a vocal defender of the theory. Speaking at a press conference in 1975, Kissinger said, “We must understand that peace is indivisible. The United States cannot pursue a policy of selective reliability. We cannot abandon friends in one part of the world without jeopardizing the security of friends everywhere.”
Decades later, President Reagan again referenced domino theory to explain US intervention in Latin America; Reagan argued that any communist presence in Latin America was a threat to the entire Western Hemisphere. “We believe that the government of El Salvador is on the front line of a battle that is really aimed at the very heart of the Western Hemisphere and eventually at us,” Reagan told reporters, adding that if El Salvador were to “fall” to communism, then “I think Costa Rica, Honduras, Panama and all of these would follow.”