Answer:
a revolution that brought a communist to power
Step-by-step explanation:
It was not the Cuban army that cause tension. Too far and unimportant as an isolated event. It wasn't the missile crisis since it happened in the 60s. It wasn't also the deportation of Cuban immigrants since there's nothing wrong with deporting illegals, generally speaking. What caused a great shift was the revolution that took down the government of Cuba and installed a communist dictatorship led by Fidel Castro.