Venezuela's President Nicolas Maduro, right, greets supporters during an awards ceremony for athletes in La Guaira, Venezuela December 18, 2014. U.S. move to normalize relations with Cuba could weaken Venezuela, improve ties to other countries. (Handout/Reuters)

With shouts of “Viva Fidel!” Cuban President Raúl Castro said Saturday that the easing of tensions with the United States did not mean he was going to jettison the communist ideals that his brother brought to the island a half-century ago.

In a speech to the Cuban parliament, during which he honored the return of three Cuban spies who were part of a prisoner swap with the United States, Castro thanked President Obama for his decision to reestablish diplomatic relations.

But he reiterated the principles of the communist revolution and suggested that change would not come quickly to Cuba.

“We must not expect that in order for relations with the United States to improve, Cuba will abandon the ideas that it has struggled for,” he said.

Castro’s speech highlighted the tricky road ahead for relations between the two longtime antagonists. The Cuban detente may not mean rapid economic or political change on the island. But it has already reshuffled the deck politically in Latin America.

1 of 16 Full Screen Autoplay Close Skip Ad × U.S. and Cuba move to end more than five decades of enmity View Photos The superpower and the Communist-ruled island nation exchange prisoners and begin to overhaul relations shaped by a complicated and troubled history. Caption The two nations exchange prisoners and begin to overhaul relations. Jan. 8, 1959 Cuba’s Fidel Castro speaks to supporters at the military base Columbia, now known as Ciudad Libertad, after dictator Fulgencio Batista fled the country on New Year’s Day, sealing the triumph of the Cuban Revolution. AP Buy Photo Wait 1 second to continue.

Castro said Saturday that he would attend a regional meeting with the U.S. president and other leaders in Panama in April. When Obama walks into the Summit of the Americas, the man considered the imperialist-in-chief by some Latin American leaders is likely to face a much warmer crowd.

With his decision last week, Obama swept away a decades-long grudge held not just by the aging communist regime but by some of the staunchest American allies in the region.

“This makes it so much easier for the U.S. to relate to its allies and friends in the region,” said Christopher Sabatini, senior director of policy at the Americas Society and Council of the Americas.

The new U.S. policy also weakens the position of one of the most vocal American critics in the region, President Nicolás Maduro of Venezuela. His country has been Cuba’s biggest supporter, sending it millions of barrels of oil. But falling oil prices have led to a severe economic crisis in Venezuela, causing rising inflation and shortages of food and other basic necessities and reducing the country’s influence in the region. And now Cuba has reached a deal with the Americans.

“It totally marginalizes Maduro and his government,” Sabatini said. “Clearly, Raúl Castro is diversifying his assets and his options.”

A day after Obama announced the Cuba changes, he imposed stiff new sanctions on Venezuela. The decision to deny visas and freeze the assets of some Venezuelan officials accused of human rights violations this year struck some analysts as a concession by the Obama administration to the anti-Castro voices in Congress.

“I think those things clearly are related,” David Smilde, a senior fellow at the Washington Office on Latin America, said Friday from Venezuela.

A difficult history between U.S. and Cuba More than 50 years after the U.S.-imposed embargo, President Obama has announced an effort to normalize ties with Cuba.

(Kennedy Elliott, Julie Tate and Swati Sharma/Staff reports)

The changed relationship with Cuba “makes it a little bit more difficult for the Maduro government to argue that the Obama government is imperialist and controlling its back yard,” he said. The imposition of sanctions, meanwhile, “gives Obama cover about being soft on dictators.”

Maduro, for his part, initially praised Obama for his courage in making the overture to Cuba but then responded harshly to the sanctions. The successor to Hugo Chávez described on Twitter the back-to-back moves by the Obama administration as the “contradictions of an empire that seeks to impose its domination by whatever means.” He said they showed that the U.S. government was opening a “new phase of aggressions” against Venezuela.

U.S. officials hope that they can start a more productive chapter with anti-American stalwarts in Latin America such as Bolivia and Ecuador — whose leaders have used the conflict between Washington and Havana to strengthen their arguments that America is a regional bully. And some analysts predict that Obama will gain leverage in the region to push Venezuela harder on human rights issues.

The longtime resentment in the region about the embargo on Cuba has grown in recent years as more left-wing governments have come to power in Latin America and more leaders viewed the policy as an unfair and ineffective relic.

While Obama’s Cuba shift was received positively in Latin America, some people in the region worry it could pose a business threat to them as U.S. agricultural firms, airlines, cruise operators and Internet and telecom companies move to take advantage of the island’s market. Some tourism operators in popular Mexican destinations such as Cancun have worried that they might lose business as Americans opt instead for Cuban beaches.

Brazil has invested heavily in Cuba, including contributing $800 million to help build the Mariel free-trade zone and container port that opened last year.

The U.S. opening toward Cuba “basically challenges Brazil’s role [in Cuba] in many ways,” Sabatini said.

Mexican President Enrique Peña Nieto talked by phone with Castro on Thursday, congratulating him on the agreement and inviting him to Mexico, according to a statement from the Mexican presidency. Castro, the statement said, welcomed further investment by Mexican companies in Cuba. Fidel Castro and Che Guevara planned their revolution in the 1950s in Mexico, which has maintained diplomatic and economic ties with Cuba over the years.

The U.S. government now moves to the nuts and bolts of “normalizing” relations. Some of that work is fairly formulaic, such as ending the role of the Swiss government as a “protecting power” over U.S. interests in Cuba or changing the title of chief of mission at the U.S. Interests Section in Havana to a charge d’affaires at an embassy (the harder part is receiving Senate confirmation of a new ambassador). There are other issues to discuss in the near-term, such as caps on the number of diplomats and their freedom of movement in each country.

Details also must be worked out for the changes on trade, travel and banking transactions that Obama announced. The first high-level meetings to discuss the next steps will take place next month when Roberta Jacobson, the State Department’s assistant secretary in charge of Latin American affairs, will travel to Havana.

Some officials expect that the overall embargo could be the next casualty, given the international support for Obama's measures. Lifting the embargo, however, would require congressional approval.