The CIA assassination attempts on Fidel Castro are best be explained as folllows.
As we all know, Fidel Castro was the dictator of Cuba for more than 40 years. Unfortunately, being a communist, or socialist... or not a capitalist supporting dictator, during the Cold War comes with certain complications (The United States will do anything to kill you), and as stated above, there were more than 634 attempts on Castro's life.
It all started with the Bay of Pigs. If you don't already know what this is, it basically went something like this: Castro went over to Cuba with Che Guevara. They fucked shit up and then he said, "I am Fidel Castro and we have come to liberate Cuba." A bunch of Cubans were like, "Eff this guy" and they drifted over to the US on some mattresses and other floating shit. The CIA rounded them up and trained them all to shoot. Then they were sent back to take over Cuba and they all got killed. Attempt number one... Fail. The CIA then asked themselves, "How could such a brilliantly conceived plan not work?"
Their next attempt involves the Mafia. Before Castro took over, the Mafia was making bank in Cuba from casinos, brothels, drugs, extortion and whatever else the Mafia does. However, these money making methods worked alongside capitalist ideas. When Castro came to power he told them to fuck off or he would kill them. Therefore the CIA thought it would be a great idea to pay the Mafia to kill Castro because they already had beef with him. They soon found that the Mafia didn't give a shit. They just took the government's money and did nothing. Mafia attempt... Fail. The CIA again asked themselves, "How could this flawless plan not work?"
That's when they took matters into their own hands. President Kennedy put his brother Robert in charge of killing Castro. Next came car bombs, poisonous cigars, poisoned pills, exploding mollusks, chemically tainted scuba diving wet suits, snipers, exploding cigars and anything imaginable that could kill a man. But, the everything else attempt, yet again... Fail. Castro lived and now the CIA was like, "What is with this guy?"
That's when the answer dawned on them. It must be the beard. The CIA, believing Castro's beard possessed some sort of super power that made him immortal, made their next plan of action to destroy it. Believe it or not, this actually happened (the destroying the beard part at least, I am only about 60% sure they thought it made him immortal. Other reasons could be that it was intimidating or that it made him look awesome). Anyway, they gave him some powder that was suppose to make his beard fall out. It didn't work. Then they gave up.
The only thing they didn't try:
Big Giant Rocket
Andy Samberg said, "All great men have moustaches." Coming from Andy Samberg this has to be true, but the CIA took it a step further assuming that all great men have moustaches "and or beards." Both statements are true.