President Trump’s secretary of state and national security adviser has long sought to cripple or topple Cuba’s government, which has close security and economic ties to Venezuela.

A pre-dawn phone call jolted President Trump awake. His national security adviser had urgent news about Venezuela.

Protests were erupting, soldiers had defected, and the country’s autocratic leader, Nicolás Maduro, had been hustled to a military compound. It looked like he could be forced from power. “Wow,” Mr. Trump said, according to a memoir by John R. Bolton, the national security adviser at the time.

That hopeful moment for Mr. Trump, in his first term, was short-lived. Partly because of help Mr. Maduro got from Cuba, the revolt failed, according to administration officials. That disappointed not only the president and his top aides, but also Marco Rubio, the Republican senator from Florida who had been a driving force in seeking the ouster of the Venezuelan leader.

Nearly seven years later, Mr. Maduro is still in power. Mr. Rubio, now Mr. Trump’s secretary of state and interim national security adviser, is a primary architect of an escalating military pressure campaign against Venezuela. And while pushing out Mr. Maduro appears to be one immediate goal of U.S. policy, doing so could help fulfill another decades-long dream of Mr. Rubio’s: dealing a critical blow to Cuba.

“Their theory of change involves cutting off all support to Cuba,” said Juan S. Gonzalez, who was President Joseph R. Biden Jr.’s top White House aide for Western Hemisphere affairs. “Under this approach, once Venezuela goes, Cuba will follow.”

Mr. Rubio has hinted at the idea in public, telling NPR in early 2019 that a weakened Cuba would be a welcome “byproduct” of a change in Venezuela’s government, even if it were not “the central rationale” for pushing out Mr. Maduro. “Anything that’s bad for a communist dictatorship is something I support,” he said.

In private, he has been more direct. As a senator, Mr. Rubio routinely discussed Mr. Maduro’s support for Havana in detail with his colleagues, as well as with U.S. officials and foreign diplomats, according to a former Senate aide who was often present for the discussions. The former aide said Mr. Rubio had “articulated a vision” in which splitting Venezuela from Cuba would have disastrous consequences for the Cuban government.

“It all goes back to Cuba — anything he can do to weaken the regime in Cuba,” said another U.S. official who was in briefings with Mr. Rubio during the first Trump administration.

In 2019, Mr. Rubio and aides to Mr. Trump took what they saw as an important lesson from the failed push against Mr. Maduro that April: Cuba had been the pivotal player in saving Mr. Maduro, not his people or his generals.

Cuban intelligence had tipped off Mr. Maduro to the plot, and Cuban operatives inside his country helped him crush it, Mr. Bolton and other former officials said. Cuba also had a plane waiting, ready to whisk Mr. Maduro away — to Havana, Trump officials said at the time.

Posting on social media during that period, Mr. Rubio rejected the idea that Mr. Maduro was the target of a coup attempt, noting that the United States did not consider him a legitimate ruler.

“The only coup is the one carried out by Cuba in support of dictator Maduro,” Mr. Rubio wrote.

To Mr. Rubio and other U.S. officials, including ones in the Biden administration, the 2019 episode underscored the deep ties between Venezuela and Cuba, whose leftist leaders have stymied American presidents since Dwight D. Eisenhower.

With its proximity to Florida’s southern tip, its communist ideology, the historical resonance of the 1962 Cuban missile crisis and, not least, the political power of South Florida’s large Cuban American community, the island has long held an outsize grip on policymakers in Washington.

Venezuela and Cuba enjoy an economic, political and security partnership that Cuban leaders work hard to protect, fearing that Mr. Maduro’s downfall and possible replacement by a U.S.-backed leader might threaten their own survival.

In recent months, the U.S. military has built up a large force near Venezuela. It is attacking boats and killing people aboard who Mr. Trump and Mr. Rubio say, without presenting evidence, are smuggling drugs — strikes that many legal experts have deemed illegal. It is all part of a campaign to pressure Mr. Maduro to step down or to forcefully oust him, one that has no congressional authorization.

When Mr. Trump spoke by phone to the Venezuelan leader last month, he demanded that Mr. Maduro abdicate power, an administration official said. On Wednesday, Mr. Trump announced that the United States had seized a tanker with Venezuelan oil.

Even as Mr. Trump and Mr. Rubio have framed the push against Mr. Maduro as part of a crackdown on drug trafficking from Latin America, Cuba hawks see the potential to deal a blow to the government in Havana.

A Cuban opposition figure, José Daniel Ferrer, who fled to the United States in October after being released from prison and met with Mr. Rubio, said in an interview that deposing Mr. Maduro “would also favor the fall, or possible fall, of the regime in Havana, which is the matrix of evil.”

Mr. Ferrer said he and Mr. Rubio discussed the ties between Venezuela and Cuba in their State Department meeting last month.

Wishful talk, some say. The Cuban government has survived decades of isolation since the collapse of the Soviet Union, its Cold War ally. It continues to benefit from two powerful patrons, Russia and China, and is less reliant on Venezuela than it was a decade ago. U.S. sanctions on Venezuela and the resulting economic collapse have forced Mr. Maduro to reduce his oil exports to Havana in recent years.

For Mr. Rubio, seeing Cuba’s government crumble would be a lifelong dream come true.

Mr. Rubio’s parents, Mario and Oriales, immigrated to Florida from Cuba three years before the triumph of Fidel Castro’s communist revolution in 1959. Rising through Florida Republican politics, Mr. Rubio cast himself as a sworn enemy of Mr. Castro (“an evil, murderous dictator”) and his successors.

In Florida, a state with more than two million residents of Cuban and Venezuelan ancestry, most of them Republican voters, it was a powerful match of message and messenger.

As a senator, Mr. Rubio constantly spotlighted political repression and human rights abuses in Cuba, and opposed any efforts to relax U.S. pressure on its government. When Mr. Rubio announced a bid for president in 2015, he did so from the Freedom Tower in Miami, a former processing center for Cuban refugees fleeing Mr. Castro’s government.

“Rubio emerges out of the anti-Cuban politics of Miami,” said Benjamin J. Rhodes, a former deputy national security adviser to President Barack Obama.

Mr. Rhodes managed Mr. Obama’s partial restoration of U.S. economic and diplomatic ties with Cuba and interacted with Mr. Rubio at the time. “He’s always been rooted in a regime change policy toward Havana — it’s core to his identity,” Mr. Rhodes said.

“There’s always been an article of faith in Miami that if the Venezuelan domino falls, the Cuban domino will follow,” he added.

Since joining the Trump administration, Mr. Rubio has pressed his cause directly, ordering new sanctions on Cuban government officials, activities and businesses.

Asked for comment about Mr. Rubio’s views on Cuba and Venezuela, the State Department said both regimes were “destabilizing to the entire hemisphere” and added that the Trump administration was waging an antidrug campaign to protect Americans from the threat of “poison shipped into our country by terror organizations.”

Mr. Trump, for his part, seems less personally invested in the fate of Cuba, even if in January he renewed his earlier designation of Cuba as a state sponsor of terrorism.

As a candidate in 2015, Mr. Trump initially said Mr. Obama’s outreach to Havana was “fine,” before adopting a harder line more in sync with his party’s. In 2019, speaking in Miami to an audience of Venezuelans, he declared “nothing could be better” for the future of Cuba “than the rebirth of freedom and democracy in Venezuela.”

The Crucible

The modern Cuba-Venezuela partnership emerged from Mr. Castro’s admiration for Mr. Maduro’s predecessor, Hugo Chávez, a champion of the poor who staged a failed revolution before winning an election to take power as president in 1999.

Both men were swaggering autocrats who denounced free markets and American imperialism while celebrating their socialist brotherhood. Mr. Chávez even hosted Mr. Castro in Caracas on the Cuban leader’s 75th birthday, leading a crowd of thousands in singing “Happy Birthday.”

Under Mr. Chávez, Venezuela began delivering Mr. Castro’s government nearly 100,000 barrels of heavily discounted oil per day, a critical lifeline for a Cuban economy stunted by decades of U.S. sanctions. In return, Mr. Castro sent thousands of military and intelligence officials who helped train — and monitor — Mr. Maduro’s security forces.

Mr. Gonzalez, the former Biden aide, cautioned that the role of Cubans in Venezuela was often overstated. But, he said, they do advise Mr. Maduro, conduct counterintelligence operations and enforce loyalty.

“All the members of the military and those in presidential security are locked down,” he said. “They’re handpicked and are watched like hawks. If they get out of line, they end up in prison and tortured to death.”

That has made it difficult for the United States to compel military officers to turn on Mr. Maduro, Mr. Gonzalez said.

Cuba has also sent thousands of medical workers to Venezuela to assist the country’s failing medical system. They have provided important care, but Mr. Maduro has also manipulated some of their services to secure votes for his coalition in elections.

The oil-for-security pact survived the deaths of Mr. Chávez and Mr. Castro. But strict sanctions imposed by Mr. Trump in his first term, and maintained by President Joseph R. Biden Jr., have hampered Mr. Maduro’s ability to share resources. Venezuela now sends Cuba around 27,000 barrels per day, according to recent data from PDVSA, the Venezuelan state-owned oil company, Reuters reported on Friday. That is barely a quarter of the amount Cuba received in Mr. Chávez’s heyday.

Experts say that the number of Cuban professionals in Venezuela has also dropped, although accurate numbers are elusive.

The wooden Mr. Maduro, who took power in 2013, lacks his predecessor’s grandiose charisma, but he remains Latin America’s only other socialist revolutionary leader in the spirit of Mr. Castro. His most prominent political rival is Venezuela’s opposition leader, María Corina Machado, a conservative free-marketeer long backed by Mr. Rubio. The secretary of state formally supported her nomination for the Nobel Peace Prize, which she won in October.

Even with diminished Venezuelan support, Mr. Rhodes said, it is clear that Havana is determined to protect Mr. Maduro.

“The Cubans must believe that if Maduro is removed and you have a right-wing government ascendant in Venezuela, that could be the straw that breaks the back of an already-weakened Cuban government,” Mr. Rhodes said.

But that sort of thinking could be dangerous, he added. “Cuba is far more likely to collapse and become a failed state than it is to have some kind of a neat transition to a Miami-backed government,” Mr. Rhodes said.

And Mr. Rubio’s approach to Venezuela and Cuba involves political risk to himself, as critics see the specter of costly “regime change” policies that the U.S. has tried and failed. They include some of Mr. Trump’s die-hard supporters, such as the former White House strategist Stephen K. Bannon, the podcast host Tucker Carlson and the informal Trump adviser Laura Loomer.

Cuba has a singular pull on Latin America hawks, and especially for those from diaspora families like Mr. Rubio’s, said Curt Mills, executive director of The American Conservative magazine, which opposes U.S. regime change efforts. Those hawks see leftist governments in the region, from Nicaragua to Venezuela, “as ultimately rather hapless appendages of Havana.”

“Cuba,” he said, “is the crucible.”