1) 1952: People haven't quite caught on to the fact that Czechoslovakia is a puppet regime of the URSS, as such, Czech citizens can freely travel to Brazil, who saw them as a free nation. This made it quite easy for the Czech secret police (StB) to operate in the country. The StB, of course, took orders straight from Moscow. After the fall of the Soviet Union, the documents the StB kept were released, and they now reside in Prague. The documents detail the operations the StB undertook in Brazil through the next decade. A book was written in detail about the documents titled "1964, O Elo Perdido – O Brasil nos arquivos do serviço secreto comunista".

2) 1952-1961: StB operations in the country reach critical levels during this period, according to documents from the organization, the network of agents was vast. It included people from all manners of society, journalists, nationalist activists, parliamentarians(!!!), state governors(!!!), businessman, public servants, and people close to the president Jânio Quadros. The StB produced reports in excruciating detail about everything possible about Brazilian life, up to what brands they preferred and general lifestyle. The plan was clear: the USRR was plotting to transform Brazil in another one of its puppet states, through a communist revolution, as they would do to many other states such as Vietnam, Cuba, South Korea, and East Germany. The situation towards 1961 is getting pretty bad.

3) 1961: Jânio Quadros is elected on an independent foreign policy platform, this is important because Cuba is starting to get spicy around now, and Brazil was to assume a middle, neutral position towards the conflicting US and URSS. Quadro's term is short and marked by strong intrigue. As you would expect, the StB was pushing for a position were Brazil would side with Cuba and Quadros was quickly running out of allies. Finally, in the summer of that same year, Quadros unexpectedly resigned, on his note of resignation he cites " foreign and terrible occult forces (sic)".

4) 1961-1962: João Goulart is elected president of Brazil, and he is a leftist. Congress is reluctant to accept him as Quadros's successor but a deal is reached. Goulart would side with Cuba now formally opposing sanctions in the country and resuming relations with the Soviet Union.

5) 1962: Cuban missile crisis time, Brazil acts as a mediator passing messages from the American government to the Soviet Union.

6) 1962-1963: The Americans start to catch on to what is going on here. The best source on this period is the NSA archives here: (https://nsarchive2.gwu.edu/NSAEBB/NSAEBB465/).
During this period, Washington would demand that Goulart stop playing with what he called "ultra-radical anti-Americans" in Brazil's government, this was the peak of StB activity in the country. Kennedy decided to upgrade contacts with the Brazilian military by bringing in a new US military attaché-Lt. Col. Vernon Walters, noting: "We may very well want them [the Brazilian military] to take over at the end of the year, if they can."
On December 11, 1962, the Executive Committee (EXCOMM) of the National Security Council met to evaluate three policy alternatives on Brazil: A. "do nothing and allow the present drift to continue; B. collaborate with Brazilian elements hostile to Goulart with a view to bringing about his overthrow; C. seek to change the political and economic orientation of Goulart and his government." [link to document 2] Option C was deemed "the only feasible present approach" because opponents of Goulart lacked the "capacity and will to overthrow" him and Washington did not have "a near future U.S. capability to stimulate [a coup] operation successfully." Fomenting a coup, however "must be kept under active and continuous consideration," the NSC options paper recommended.
Acting on these recommendations, President Kennedy dispatched a special envoy — his brother Robert — to issue a face-to-face de facto ultimatum to Goulart. Robert Kennedy met with Goulart at the Palacio do Alvarada in Brazilia on December 17, 1962. During the three-hour meeting, RFK advised Goulart that the U.S. had "the gravest doubts" about positive future relations with Brazil, given the "signs of Communist or extreme left-wing nationalists infiltration into civilian government positions," and the opposition to "American policies and interests as a regular rule." As Goulart issued a lengthy defense of his policies, Kennedy passed a note to Ambassador Gordon stating: "We seem to be getting no place." The attorney general would later say that he came away from the meeting convinced that Goulart was "a Brazilian Jimmy Hoffa."
As the CIA continued to report on various plots against Goulart in Brazil, the economic and political situation deteriorated. When Kennedy convened his aides again on October 7, he wondered aloud if the U.S. would need to overtly depose Goulart: "Do you see a situation where we might be—find it desirable to intervene militarily ourselves?" The tape of the October 7 meeting — a small part of which was recently publicized by Brazilian journalist Elio Gaspari, but now transcribed at far greater length here by Hershberg — contains a detailed discussion of various scenarios in which Goulart would be forced to leave. Ambassador Gordon urged the president to prepare contingency plans for providing ammunition or fuel to pro-U.S. factions of the military if fighting broke out. "I would not want us to close our minds to the possibility of some kind of discreet intervention," Gordon told President Kennedy, "which would help see the right side win."
Under Gordon's supervision, over the next few weeks the U.S. embassy in Brazil prepared a set of contingency plans with what a transmission memorandum, dated November 22, 1963, described as "a heavy emphasis on armed intervention." Assassinated in Dallas on that very day, President Kennedy would never have the opportunity to evaluate, let alone implement, these options.

7) 1964: on March 31, the Brazilian military would launch a coup d'etat on João Goulard. Fearing a civil war scenario, the US started to mobilize its forces, a tanker was planned to reach Santos in 11 days to aid the Brazilian armed forces and protect American citizens and companies on Brazilian soil. The coup went smoothly, however, and no American boots actually made it to Brazil.

The Brazilian military would now seize control of the country, but StB insurgents would continue to be a problem.