WASHINGTON >> Fidel Castro’s passing removes what was long the single greatest psychological barrier to a warmer U.S.-Cuba relationship. But it also adds to the uncertainty ahead with the transition from an Obama to a Trump administration.

“A brutal dictator” of a “totalitarian island,” declared President-elect Donald Trump, underscoring the historical trauma still separating the countries.

A more restrained President Barack Obama, carefully promoting and working to preserve his own attempt to rebuild those ties, said history would assess Castro’s impact and that the Cuban people could reflect “with powerful emotions” about how their longtime leader influenced their country.

In death as in life, Castro has divided opinion: a revolutionary who stood up to American aggression or a ruthless dictator whose movement trampled human rights and democratic aspirations.

President Raul Castro, Fidel’s younger brother, is 85. Their Communist Party shows no signs of opening up greater political space despite agreeing with the United States to re-establish embassies and facilitate greater trade and investment.

As Obama leaves office in January, his decision to engage rather than pressure Havana in the hopes of forging new bonds could quickly unravel. Trump has hardly championed the effort and Republican leaders in Congress fiercely opposed Obama’s calls to end the 55-year-old U.S. trade embargo of the island.

“We know that this moment fills Cubans — in Cuba and in the United States — with powerful emotions, recalling the countless ways in which Fidel Castro altered the course of individual lives, families and of the Cuban nation,” Obama said.

He offered neither condemnation nor praise for Castro, who outlasted invasion and assassination plots, and presided over the Cuban missile crisis, which took the world to the brink of nuclear war.

“History will record and judge the enormous impact of this singular figure on the people and world around him,” Obama said, adding that U.S.-Cuban relations shouldn’t be defined “by our differences but by the many things that we share as neighbors and friends.”

Trump didn’t pass off his evaluation to the historians.

“Today, the world marks the passing of a brutal dictator who oppressed his own people for nearly six decades,” Trump said in a statement. “Fidel Castro’s legacy is one of firing squads, theft, unimaginable suffering, poverty and the denial of fundamental human rights.”

Trump expressed hope that Castro’s death would mark a “move away from the horrors” toward a future where Cubans live in freedom. But he said nothing about Obama’s project to reset ties, and even hailed the election support he received from veterans of the failed 1961 Bay of Pigs invasion that was backed by the CIA.

Such a statement probably will irritate Havana, coming after a two-year period of intense diplomatic discussions with Washington that have done more to improve relations between the countries than anything in the past 5 ½ decades.

Castro’s reign began when his improbable insurrection ousted the U.S.-backed strongman Fulgencio Batista in 1959. Only 32 at the time, Castro was the youngest leader in Latin America and inspired revolutionaries as far afield as Africa and Asia.

But Castro’s socialist Cuba was anything but an idyll, and the United States quickly became his fiercest opponent.

Members of Batista’s government went before summary courts, with at least 582 executed by firing squad in the first two years of Castro’s rule. Independent newspapers were closed. Gays were herded into camps for “re-education.” Tens of thousands were held as political prisoners. Hundreds of thousands of Cubans fled. After the Soviet Union vanished, Cuba’s economy collapsed.

In Miami and other American cities, a powerful emigre community emerged that was bitterly opposed to any improvement in U.S. relations with Castro’s government. For many years, their threat alone was enough to sink any attempts to bridge divides.

The dynamic began changing a decade ago, as Castro stepped back from public life. His health ailing, he handed over power to brother Raul in 2008 and a period of limited economic reforms was ushered in.

After Cuba’s government released American prisoner Alan Gross and agreed to a spy swap with Washington in 2014, Obama and Raul Castro felt they finally had enough trust to embark on a journey of rapprochement.

While some U.S. investment has opened up and travel rules for Americans are now greatly eased, the normalization has been limited because Obama could never get Republican lawmakers to end the vast restrictions tied up in the trade embargo. Triumphant alongside Trump in November, some GOP leaders have vowed to reverse Obama’s effort.

“Now that Fidel Castro is dead, the cruelty and oppression of his regime should die with him,” House Speaker Paul Ryan, R-Wis., said in a statement Saturday. “Sadly, much work remains to secure the freedom of the Cuban people.”

Democratic Sen. Amy Klobuchar of Minnesota, who is pushing legislation to scrap the embargo, said in an interview that Castro’s shadow “loomed over all the government’s decisions” even though he had left power. She hoped Trump and Republican leaders would respond to Castro’s death by at least not rolling back Obama’s openings to Cuba and perhaps advancing them.

During his campaign, Trump criticized Obama for striking a “very weak agreement” and threatened to reverse Obama’s executive orders “unless the Castro regime meets our demands.” He never laid out those demands, and at other times hinted about being amenable to more U.S. investment in Cuba.

As with much of his foreign policy, Trump never outlined clearly a set of policy objectives with Cuba. The ambiguity leaves much of the recent warming on uncertain ground. It’s unclear if Castro’s death, however powerful for castigators and champions, will dramatically sway Trump one way or the other.