Answer:
It suggested that the United States would need to support governments fighting communism
Step-by-step explanation:
The domino theory held that if one region fell to communism, other countries in the region would also fall like a row of dominoes (one right after the other).
Domino theory began to be used as a shorthand expression of the strategic importance of South Vietnam to the United States, as well as the need to contain the spread of communism throughout the world.