President Eisenhower’s metaphor was the metaphor of dominoes. Eisenhower likened the countries of the world to dominoes stood on end in a row. One domino being tipped over (becoming communist) would knock the next over and so on until all the dominoes had fallen.
This idea helped to shape American foreign policy during the Cold War because it made it seem as if any threat from communism anywhere could be a danger to the US. If Vietnam fell, for example, so would all the other countries of Asia. Eventually, this would mean that the Philippines and Japan would fall and America would lack allies and bases in Asia.
Thus, Eisenhower’s domino metaphor helped convince policy makers that communism had to be resisted even in places far from the United States.