Answer:
The Americans were concerned when Fidel Castro overthrew Cuban dictator Fulgencio Batista because upon coming in power, Castro made a trading deal with the Soviet Union. He started to put American business in jeopardy.
Step-by-step explanation:
The Americans were concerned because when Fidel Castro came into power, he started to maintain relations with the Soviets which angered the Americans. The cold war grew stronger each day when Castro seized American businesses and they had to face lose over $100 million.
Later, Castro announced that he was a communist. This news threw Americans off the edge completely and they immediately declared an economic blockade of the Cuba.