The Bolsheviks came to power for three key reasons which were?

The interim government was toppled, the Soviets seized power, and Russia later terminated the Triple Entente military alliance with France and Britain. For Russia, it was effectively the end of the war.

Explanation: The one in 1917^

the lowest among the social higher rank were the working class. this class remained detached to the political progression   of the country and was hostile to the other two classes

so, based on the research i've done. the u.s. government were always on a wild goose chase just to take down castro. he then retired his trone to his brother raul in 2008 due to some health issues. so it's obvious your answer would be:

castro had no allies from which he could receive aid.

hope this and have a fantastic day!

                                                    -wolfiewolffromsketch