Was communism a threat with the domino theory?

The Domino Theory, as stated by President Eisenhower in regard to Southeast Asia, stated that the practice of Communism in one country would cause nearby countries to fall to the "spread" of communism, like a series of falling dominoes. However, the accuracy of this theory is still under debate, even today. On one hand, the theory is supported by the fact that South Vietnam, Cambodia and Laos all became Communist nations after America pulled troops out of Vietnam, thereby "preventing" the proliferation of Communism. This seems to support the theory, as without American intervention, several neighboring countries established Communist governments, all one-after-the-other. However, on the other hand, Communism did not spread any farther than that, even though Eisenhower had claimed that it would. The fact is, other countries in the region, such as Indonesia and Thailand, remained untouched. The American government was worried about a unified Communist block that would extend through Asia via the Domino Theory, but this was also disproven when two Communist nations, Cambodia and Vietnam, waged war against each other, thereby shattering beliefs that Communism in Southeast Asia was a unified network of countries.