The detente between the U.S. and Cuba after nearly 54 years of mutual hostility has the potential to redraw political and economic alliances across the hemisphere that have endured since the Cold War, government officials, diplomats and scholars say.

"We can see that the agreement between the United States and Cuba has created an opening for the entire region to rethink its relationship to the U.S. and each other," said Milos Alcalay, a former United Nations ambassador under former Venezuelan President Hugo Chávez.

But it won't be easy for every country to give up long-held animosity toward El Imperio--the empire--as some in the region call the U.S. No country is more likely than Venezuela to feel the effects of the U.S.-Cuba thaw.

Mr. Alcalay said that his country, which for more than a decade has been Cuba's closest ally as well as a fierce Washington critic, must decide whether to "maintain its hostile posture toward the U.S." or follow Cuba's example in establishing more constructive links with its northern neighbor.

So far, Mr. Maduro is maintaining a hostile stance.

As President Barack Obama signed congressional sanctions against Venezuelan officials for alleged human-rights abuses, Mr. Maduro tweeted that while the U.S. embargo against "our sister Cuba" failed, the U.S. has initiated "an escalation of a new stage of aggressions" toward Venezuela.

Nicmer Evans, a university professor and dissident in Venezuela's ruling party, said that the Cuba development "has swept the ground out from under the feet of Maduro in regard to his policy toward the United States."

Much of Mr. Maduro's rhetoric, Mr. Evans noted, is "fundamentally based on the anti-imperialist struggle and the condemnation of the American blockage against Cuba." With the normalization of ties between Washington and Havana undermining that rationale, Venezuela's leadership needs to reconfigure the country's relationship with the U.S., Mr. Evans said.

The U.S.-Cuba rapprochement could remove a long-standing obstacle to warmer relations between Washington and other Latin countries as well.

"I think a constructive dialogue with Cuba has placed us in a much better place strategically to talk to countries like Argentina, Ecuador and others," said Alana Tummino, who heads the Cuba Working Group of the Americas Society and Council of the Americas. "Where before we could be criticized for our isolation policy, we can move past that now."

As an example, Ms. Tummino pointed to a previous flurry of speculation about whether Cuba would be welcomed at the coming Summit of the Americas next year. With the new accord, she said, the summit's focus can shift to other, more substantial policy issues, even though Cuba is expected to attend.

"Engaging with Cuba is going to change not only how we interact with Cuba but also the region," she said.

For the last half-century, the antagonistic U.S.-Cuba relationship has created political fault lines large and small across Latin America. A visit by Fidel Castro to Chile helped precipitate Gen. Augusto Pinochet's political coup against leftist President Salvador Allende. Cuba and the U.S. backed opposite sides in the civil wars that scarred Central America in the 1980s.

Support for the Castro regime helped split some Latin American political parties into center-left and hard-left factions. Intellectuals took sides in the ideological struggle between capitalism and communism, the most prominent being Nobel Prize-winning novelist Gabriel García Márquez, who had a close personal friendship with Fidel Castro.

And Cuba still plays an outsize role for its relatively small size, said Cynthia Arnson, director of the Latin America program at Washington's Woodrow Wilson Center.

In Colombia, the U.S.-Cuba accord coincides with Havana's active role in helping to broker a peace accord to end a half-century-old war between Marxist rebels and the Colombian government.

"Cuba has been an important reference for the guerrillas in Colombia," who may now see negotiations as a better way to settle the conflict, said Aldo Civico, a conflict resolution expert at Rutgers University who is close to the negotiators in Havana.

At the same time, Mr. Civico said, the U.S.-Cuba agreement also may help sway Colombians who have been skeptical of sitting down at the table with armed rebels. "It's a boost of optimism and a sign that it is possible to resolve a problem even though it transcended generations," said Mr. Civico.

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