Since the middle of the 18th century Cuba had been the crown jewel of the Spanish colonial empire. In the late 19th century, Cuban nationalist revolutionaries rebelled against Spanish dominance, resulting in three liberation wars: the Ten Years' War (1868–1878), the Little War (1879–1880) and the Cuban War of Independence (1895–1898). The United States government proclaimed war on the Spanish Empire, resulting in the Spanish–American War (1898). The US subsequently invaded the island, and forced the Spanish army out. On 20 May 1902, a new independent government proclaimed the foundation of the Republic of Cuba, with US Military governor Leonard Wood handing over control to President Tomás Estrada Palma, a Cuban-born US citizen. Subsequently, large numbers of US settlers and businessmen arrived in Cuba, and by 1905, 60% of rural properties were owned by non-Cuban North Americans. Between 1906 and 1909, 5,000 US Marines were stationed across the island, and returned in 1912, 1917 and 1921 to intervene in internal affairs, sometimes at the behest of the Cuban government.
Fidel Castro and the Cuban Revolution
Until Castro, the US was so overwhelmingly influential in Cuba that the American ambassador was the second most important man, sometimes even more important than the Cuban president.
— Earl E. T. Smith, former American Ambassador to Cuba, during 1960 testimony to the US Senate 
In March 1952, a Cuban general and politician, Fulgencio Batista, seized power on the island, proclaimed himself president and deposed the discredited president Carlos Prío Socarrás of the Partido Auténtico. Batista canceled the planned presidential elections, and described his new system as "disciplined democracy". Although Batista gained some popular support, many Cubans saw it as the establishment of a one-man dictatorship. Many opponents of the Batista regime took to armed rebellion in an attempt to oust the government, sparking the Cuban Revolution. One of these groups was the National Revolutionary Movement (Movimiento Nacional Revolucionario – MNR), a militant organization containing largely middle class members that had been founded by the Professor of Philosophy Rafael García Bárcena. Another was the Directorio Revolucionario Estudantil (DRE), which had been founded by the Federation of University Students (FEU) President José Antonio Echevarría (1932–1957). However, the best known of these anti-Batista groups was the "26th of July Movement" (MR-26-7), founded by a lawyer named Fidel Castro. With Castro as the MR-26-7's head, the organization was based upon a clandestine cell system, with each cell containing ten members, none of whom knew the whereabouts or activities of the other cells.
Between December 1956 and 1959, Castro led a guerrilla army against the forces of Batista from his base camp in the Sierra Maestra mountains. Batista's repression of revolutionaries had earned him widespread unpopularity, and by 1958 his armies were in retreat. On 31 December 1958, Batista resigned and fled into exile, taking with him an amassed fortune of more than US$300,000,000. The presidency fell to Castro's chosen candidate, the lawyer Manuel Urrutia Lleó, while members of the MR-26-7 took control of most positions in the cabinet. On 16 February 1959, Castro himself took on the role of Prime Minister. Dismissing the need for elections, Castro proclaimed the new administration an example of direct democracy, in which the Cuban populace could assemble en masse at demonstrations and express their democratic will to him personally. Critics instead condemned the new regime as un-democratic.
Soon after the success of the Cuban Revolution, militant counter-revolutionary groups developed in an attempt to overthrow the new regime. Undertaking armed attacks against government forces, some set up guerrilla bases in Cuba's mountainous regions, leading to the six-year Escambray Rebellion. These dissidents were funded and armed by various foreign sources, including the exiled Cuban community, the US Central Intelligence Agency (CIA), and Rafael Trujillo's regime in the Dominican Republic. No quarter was given during the suppression of the resistance in the Escambray Mountains, where former rebels from the war against Batista took different sides. On 3 April 1961, a bomb attack on militia barracks in Bayamo killed four militia, and wounded eight more. On 6 April, the Hershey Sugar factory in Matanzas was destroyed by sabotage. On 14 April 1961, guerrillas led by Agapito Rivera fought Cuban government forces near Las Cruces, Montembo, Las Villas, where several government troops were killed and others wounded. Also on 14 April 1961, a Cubana airliner was hijacked and flown to Jacksonville, Florida; resultant confusion then helped the staged 'defection' of a B-26 and pilot at Miami on 15 April.
Castro's government began a crackdown on this opposition movement, arresting hundreds of dissidents. Though it rejected the physical torture Batista's regime had used, Castro's government sanctioned psychological torture, subjecting some prisoners to solitary confinement, rough treatment, hunger, and threatening behavior. After conservative editors and journalists began expressing hostility towards the government following its left-ward turn, the pro-Castro printers' trade union began to harass and disrupt editorial staff actions. In January 1960, the government proclaimed that each newspaper was obliged to publish a "clarification" by the printers' union at the end of any article that criticized the government. This was the start of press censorship in Castro's Cuba.
Popular uproar across Cuba demanded that those figures who had been complicit in the widespread torture and killing of civilians be brought to justice. Although he remained a moderating force and tried to prevent the mass reprisal killings of Batistanos advocated by many Cubans, Castro helped to set up trials of many figures involved in the old regime across the country, resulting in hundreds of executions. Critics, in particular from the U.S. press, argued that many of these did not meet the standards of a fair trial, and condemned Cuba's new government as being more interested in vengeance than justice. Castro retaliated strongly against such accusations, proclaiming that "revolutionary justice is not based on legal precepts, but on moral conviction." In a show of support for this "revolutionary justice", he organized the first Havana trial to take place before a mass audience of 17,000 at the Sports Palace stadium; when a group of aviators accused of bombing a village were found not guilty, he ordered a retrial, in which they were instead found guilty and sentenced to life imprisonment. On 11 March 1961, Jesus Carreras and American William Alexander Morgan (a former Castro ally) were executed after a trial.
Tensions with the United States
Castro's Cuban government ordered the country's oil refineries – then controlled by US corporations Esso and Standard Oil and Anglo-Dutch Shell – to process crude oil purchased from the Soviet Union, but under pressure from the US government, these companies refused. Castro responded by expropriating the refineries and nationalizing them under state control. In retaliation, the US canceled its import of Cuban sugar, provoking Castro to nationalize most US-owned assets, including banks and sugar mills. Relations between Cuba and the US were further strained following the explosion and sinking of a French vessel, the Le Coubre, in Havana harbor in March 1960. The cause of the explosion was never determined, but Castro publicly insinuated that the US government were guilty of sabotage. On 13 October 1960, the US government then prohibited the majority of exports to Cuba – the exceptions being medicines and certain foodstuffs – marking the start of an economic embargo. In retaliation, the Cuban National Institute for Agrarian Reform took control of 383 private-run businesses on 14 October, and on 25 October a further 166 US companies operating in Cuba had their premises seized and nationalized, including Coca-Cola and Sears Roebuck. On 16 December, the US then ended its import quota of Cuban sugar.
The US government was becoming increasingly critical of Castro's revolutionary government. At an August 1960 meeting of the Organization of American States (OAS) held in Costa Rica, the US Secretary of State, Christian Herter, publicly proclaimed that Castro's administration was "following faithfully the Bolshevik pattern" by instituting a single-party political system, taking governmental control of trade unions, suppressing civil liberties, and removing both the freedom of speech and freedom of the press. He furthermore asserted that international communism was using Cuba as an "operational base" for spreading revolution in the western hemisphere, and called on other OAS members to condemn the Cuban government for its breach of human rights. In turn, Castro lambasted the treatment of black people and the working classes he had witnessed in New York, which he lampooned as that "superfree, superdemocratic, superhumane, and supercivilized city". Proclaiming that the US poor were living "in the bowels of the imperialist monster", he attacked the mainstream US media and accused it of being controlled by big business. It must be noted that, on the surface, the US was trying to improve its relationship with Cuba. Several negotiations between representatives from Cuba and the US took place around this time. Repairing financial international relations was the focal point of these discussions. Political relations were another hot topic of these conferences. The US stated that they would not interfere with Cuba's choice of government or its domestic structure; however, the US also ordered the Cubans to sever all ties with the Soviet Union.
In August 1960, the CIA contacted the Cosa Nostra in Chicago with the intention to draft a simultaneous assassination of Fidel Castro, Raúl Castro and Che Guevara. In exchange, if the operation were a success and a pro-US government were restored in Cuba, the CIA agreed that the Mafia would get their "monopoly on gaming, prostitution and drugs."
Tensions percolated when the CIA began to act on its desires to snuff out Castro. The general public became aware of the attempts to assassinate Castro in 1975 when a report entitled "Alleged Assassination Plots Involving Foreign Leaders" was released by the Senate Church Committee set up to investigate CIA abuses. Efforts to murder Castro officially commenced in 1960. Some methods that the CIA undertook to murder Castro were creative, for example: "poison pills, an exploding sea shell, and a planned gift of a diving suit contaminated with toxins." More traditional ways of assassinating Castro were also planned, such as elimination via high-powered rifles with telescopic sights. In 1963, at the same time that the Kennedy administration was initiating secret peace overtures to Castro, the Cuban revolutionary and undercover CIA agent Rolando Cubela was tasked with killing Castro by the CIA official Desmond Fitzgerald, who portrayed himself as a personal representative of Robert Kennedy.