The united states worries that if one country becomes communist then

The United States worried that if a country became communist or had a communist takeover, there would quickly be more countries that would fall to communism, like dominos. That's why this idea is called the Domino Theory. It was mainly a Cold War policy, and was the reason the U.S. got involved with Vietnam.

The Domino Theory was and still is popular, but if your question is asking about a more recent policy, please let me know and ill find some more information for you.

cuban communists pressured the soviet union to place missiles in cuba.

answer; ///(1) blank; henry clay; (2) blank; secretary of state; (c)is your answer; ///good luck