Answer:
Dwight Eisenhower was the first president to describe the domino theory in which if one country fall for communism the countries near to it will fall too during the cold war
Step-by-step explanation:
He was afraid that if South Vietnam fall in the Vietnam War then the neighbors countries will follow in a domino effect that it why the United States got involved in the Vietnam War because the president believed that it was their duty to stop the spread of communism.