The establishment of Fidel Castro as the Prime Minister for military and political power was a development that led to the situation described. With Castro in high position, he set up a Communist government that the Soviet Union recognized and opted to aid, hence the U.S.'s opposition and attempted invasion.
Explanation:
The United States was democratic and the Soviets were Communist during the Cold War, so when the U.S. saw Cuba being led by a pro-communist, they saw a potential threat and took the initiative.
