The pace and timing of rapprochement has already prompted concerns about a superficial transition.
Opinions concerning the elderly former president of Cuba are extremely divided, depending on political persuasions.
For the vast majority of the estimated 1.5 million Cuban-Americans he is the devil incarnate, a tyrant responsible for the death of thousands, the emotional separation of families and the abuse of human rights.
In Cuba, however, he is revered by most, who point to the country’s successes in healthcare and education, culture and sports. There are few shades of grey in evaluating the man who steered Cuba since taking power in 1959, leading it into the socialist camp before ceding power to his brother Raul in 2006.
Castro came from a wealthy land-holding family in the east of Cuba, where his father Angel had arrived as part of the occupying Spanish army when Cuba was still a colony of Spain.
His mother, Lina, was the family cook who married Angel several years after the birth of Fidel. The family members had significantly different political views, and in a microcosm of the polarisation of Cuban society, some members sought exile after the revolution, while others remained on the island.
Educated in private Catholic schools, Castro obtained a doctorate in law at the University of Havana and worked for several years as a legal aid lawyer.
His passion was politics, and in 1952 he was a candidate for the Cuban Congress – an election that never took place after presidential candidate Fulgencio Batista led a military coup.
Castro then turned to revolution, attempting to overthrow Batista with an attack on the military garrison in Santiago on July 26, 1953.
Arrested after the failed coup attempt, he was granted an amnesty, and moved to Mexico to regroup, subsequently returning with other Cubans – and Argentine Ernesto “Che” Guevara. After a successful military campaign between 1956 and 1958, the revolutionaries took power on January 1, 1959.
The love-hate relationship with the United States has loomed large since then, with Washington imposing an embargo on trade with the rebellious island in 1960 and breaking diplomatic relations in 1961.
The latter issue was resolved with the formal re-establishment of diplomatic relations in July 2015.
Yet, for 55 years tensions between the two countries remained high, with assassination attempts against Castro and acts of terrorism being orchestrated from the US – resulting in the deaths of some 3,400 Cubans.
Partly because of these tensions, and because of his political ideology, Cuba aligned itself with the Soviet Union after Washington broke relations with Cuba.
The former USSR and socialist countries of Europe became the major trading partners of the island, and Castro declared himself a Marxist-Leninist.
How will he be remembered? Googling 'Fidel Castro' brings up 20 million references, proof of an extraordinary interest in his role in national and international politics.
In October 1962 this alliance with the USSR brought the world close to thermonuclear war, as Soviet missiles were stationed on Cuban soil.
The implosion of the Soviet Union in 1989-90 led to major problems for Cuba, which lost more than 80 percent of its trade within a year (PDF), and a loss of 35 percent in gross domestic product.
There then followed the “Special Period”, with extensive belt-tightening in Cuba, as Castro sought desperately to maintain the survival of the revolution.
While Castro is a polarising figure for many, he is revered in developing countries, largely because of the many education and public health programmes instituted by the country.
Cuba currently has some 50,000 medical personnel working in 60 developing countries, and Cuban support has been praised effusively by many, from Nelson Mandela to Ban Ki-moon.
The Cuban experience also defied logic, with its revolution surviving despite the bitter opposition of the US only 145km away.
Now physically debilitated, Fidel Castro remains lucid, occasionally writing articles for Cuba’s official newspaper Granma, and meeting with foreign dignitaries.
He devotes his time to studying the challenges of development facing poor countries, including food production and desertification.
In March 2016, he issued a blistering critique of the visit of President Barack Obama to Havana, and warned Cuba not to be taken in by “the empire”.
Now an elder statesman, he made his last public appearance in April at a congress of the Communist Party of Cuba, at which he made reference to his death.
How will he be remembered? Googling “Fidel Castro” brings up 20 million references, proof of an extraordinary interest in his role in national and international politics.
He is seen as both a totalitarian dictator and an anti-imperialistic humanitarian. Under his rule Cuba became a symbol of resistance to the dictates of Washington – while ignoring those of Moscow.
But the historical record is very clear, and under his influence Cuba, a poor country of 11.2 million, has enjoyed widespread international attention for decades.
John M Kirk is Professor of Latin American Studies at Dalhousie University in Canada, and the author and co-editor of 16 books on Cuba, a country he has been visiting since 1976.
The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial policy.