A break from revisionist history.
Inspired by a debate comment on Renegade Eye's blog, I thought I would delve into the history between US - Cuban relations, and the reasons behind an embargo that should have ended decades ago. In part, as an answer to Sonia, and in part as a further revelation in the sordid history of international economic domination on behalf of the United States. As many of your know by now, I'm a huge fan of John Perkins. The reading that I have been doing about US relations with Cuba prior to 1959, and indeed prior to the turn of the century tells me just how long this country has been practicing the art of economically forced political alliances (AKA economic hitmen), and Dealing with the Devil, among other forms of shady international dealings.
It all starts around 1818, after trade lines opened up between Cuba and the US. Although Cuba at the time was still a Spanish colony, the United States began to see Cuba as something to be bought, had, and controlled - like a buxom woman in a tight gown. 
In 1820 Thomas Jefferson thought Cuba "the most interesting addition which could ever be made to our system of States" and told Secretary of War John C. Calhoun that the United States "ought, at the first possible opportunity, to take Cuba."
In 1854, under the document titled the Ostend Manifesto  US diplomats drew up plans to acquire Cuba from Spain for approximately $130 million dollars. The Manifesto failed when it was made public, due to anti-slavery concerns from the North. [Hugh Thomas. Cuba : The pursuit for freedom. p.134-5]
Again, in 1897, President McKinley offered to buy Cuba - this time for $300 million, and was rejected, leading into the Spanish-American War.  This war was fought by the US, to help Cuba gain its independence from Spain, when Spain refused to end the conflict peacefully, allowing Cuba to come into its own. As noble as this sounds, the US had ulterior motives, as always. Due to growing industry trade, considering the US now accounted for more than 80% of Cuban export and was a monopsony with regards to Cuban trade. Desire to make Cuba part of the US was evident enough for Henry M Teller to propose his amendment Teller Amendment which prevented the US from annexing Cuba once it was independent from Spain. It allowed for US military presence until the conflict was over, and until the government was stable, but leaving all aspects of governance to Cuba and its citizens.
At the end of the Spanish-American War, references state this:
On the 10th of December 1898 Spain and the United States signed the Treaty of Paris and in accordance with the treaty Spain renounced all rights to Cuba. The treaty put an end to the Spanish Empire in the Americas marking the beginning of United States expansion and long term political dominance over the region. Immediately after the signing of the treaty, the US-owned "Island of Cuba Real Estate Company" opened for business to sell Cuban land to Americans. U.S. military rule of the island lasted until 1902 when Cuba was finally granted formal independence.The economic dominance begins in earnest.
The neutral and somewhat vague Teller Amendment only lasted until 1901, when the Platt Amendment replaced the Teller Amendment with constrictive regulations on trade, sales, governance, and ownership of property in Cuba.
The amendment ceded to the United States the naval base in Cuba (Guantánamo Bay), stipulated that Cuba would not transfer Cuban land to any power other than the United States, mandated that Cuba would contract no foreign debt without guarantees that the interest could be served from ordinary revenues, ensured U.S. intervention in Cuban affairs when the United States deemed necessary, prohibited Cuba from negotiating treaties with any country other than the United States "which will impair or tend to impair the independence of Cuba" or "permit any foreign power or powers to obtain ... lodgement in or control over any portion" of Cuba, and provided for a formal treaty detailing all the foregoing provisions.
Although US military occupation in Cuba ended in 1902, Cuba quickly became the playground of the rich. In fact, the surge of Americans taking advantage crumbling economy due to thirty years of conflict had started long before this point, but with stricter trade agreements and property rights under the Platt Amendment, the US was ready to unofficially, and economically annex Cuba.
By 1926 U.S companies owned 60% of the Cuban sugar industry and imported 95% of the total Cuban crop, and Washington was generally supportive of successive Cuban Governments. However, internal confrontations between the government of Gerardo Machado and political opposition led to a military overthrow by Cuban rebels in 1933.
Machado's replacement, Grau nullified the Platt Amendment, presumably because it was unfair. Our government recognized this as a threat to US interests, and refused to acknowledge the Cuban government under his rule. [8, 9]
Enter in the puppet president, Batista. A general in the Army gave rise to a de facto president, and was supported by our government. (Sound familiar? We have continued this pattern in recent times.) Consider this, Grau was dismissed by our government as communist, yet Batista was actually funded and supported, at one time, by the old Cuban Communist party. Batista was also known for opening up Cuba to American gangsters, and gambling, while tightening restrictions on Cubans.
Due to growing popular opposition and unrest, manifested by the Cuban people with increasing acts of civil disobedience, and in order to appease the growing concerns in Washington, Batista held an election in 1954 in which he was the only legal candidate. Without opposition, he obviously won, becoming president of Cuba in 1954, prompting yet even more waves of civil unrest.[...]By late 1955 student riots and anti-Batista demonstration had become frequent. These were dealt with in the violent manner his military police had come to represent. Students attempting to march from the University of Havana were stopped and beaten by the police, and student leader José A. Echeverría had to be hospitalized. Another popular student leader was killed on December 10, leading to a funeral that became a gigantic political protest with a 5-minute nationwide work stoppage.
Instead of loosening his grip, Batista suspended constitutional guarantees and established tighter censorship of the media. His military police would patrol the streets and pick up anyone suspected of insurrection. By the end of 1955 they had grown more prone to violent acts of brutality and torture, with no fear of legal repercussions.
In March of 1956 Batista refused to consider a proposal calling for elections by the end of the year. He was confident that he could defeat any revolutionary attempt from the many factions who opposed him.
This is important to note, Batista was seen as a dictator, who suspended constitutional rights at least twice, and operated under the strict guidance of the US government. It is clear that Cubans objected - sometimes violently - to his rule. During his reign he allowed the US to buy up companies, and land from Cubans, regardless of the civil and economic unrest it caused with the citizens of Cuba.
Batista had always leaned toward the United States. I don't think we ever had a better friend. It was regrettable, like all South Americans, that he was known-although I had no absolute knowledge of it-to be getting a cut, I think is the word for it, in almost all the, things that were done. But, on the other hand, he was doing an amazing job.
The move was vehemently opposed by U.S. ambassador Earl T. Smith, and led U.S. state department advisor William Wieland to lament that "I know Batista is considered by many as a son of a bitch... but American interests come first... at least he was our son of a bitch."In reference to the US opting not to support Batista by supplying arms to Cuba while Castro lead the revolution that led to Batista's political demise.
Hey, at least the guy was honest about it.
When Castro with the aid of Che Guevara overthrew the US puppet government, they immediately sought changes. First and foremost, they wanted the US political influence and power plays out of Cuba. Some of the first actions taken by the new government were documented by Castro, which you can read here: The case of Cuba is the case of all underdeveloped countries. They worried about the state of the Cuban economy, and sought to nationalize companies that had been allowed to be owned by US companies. A list of companies that had been nationalized can be seen here. It should be noted that most companies are still alive and kicking today - the nationalization of said companies didn't prevent them from prospering in business outside of Cuba.
More about the nationalization of US companies can be read here. Basically, to answer Sonia's query about "taking back" companies, yes Cuba was indeed taking back companies that had been sold out from under them while being under constitutional restrictions akin to Martial Law, topped with decades of war and poverty. They didn't just take back companies however, they took back their country. The Platt Amendment had put Cuba into a trade based strangle hold, an economically crippling tactic, still used by our government today. Think about it in these terms, if someone holds you hostage, takes your things, and you get free, whats the first thing you're going to do? Get yuor things back. Thats what.
The US government sought not only to punish Cuba for its national infidelities, but other countries who sought trade with Cuba as well. Then the US froze Cuban accounts, and used the money in them to file lawsuits against Cuba. This was purely a revenge tactic.
The fact that the UN has repeatedly asked for the embargo to be stopped doesn't make a difference. The fact that other countries have come to resent the US for its stalwart position on global trade rules with Cuba, doesn't make a difference. The fact that the vast majority of Cubans enduring the punishment in the here and now had nothing to do with political power plays, revolution, or nationalization of companies doesn't matter on whit to our Government.
If the US can't have Cuba, no one can have her.