The US-Cuba rapprochement under President Barack Obama started discreetly, with few aware of the engagement.

But Russia, Cuba's longtime partner, apparently expressed dismay about the potential thaw.

President Donald Trump has largely reversed Obama's changes, which many see as a boon for Russian interests.

After a first term where trips to Latin America were dominated by criticism of the US's Cuba policy, the Obama administration decided to pursue better ties with its long-isolated Caribbean neighbor after winning a second term.

In June 2013, White House deputy national security adviser Ben Rhodes and Ricardo Zuniga, the top White House staff member on Latin America and a Cuba expert, met with Cuban officials — including Raul Castro's son — for the first time.

The discussions were discreet, privy to only a few people within the US government. By summer 2014, talks had advanced to the point where the Vatican was asked to join as a guarantor of the agreement. But other actors with interests at stake also decided to make their feelings known.

During a trip to Toronto, Rhodes and Zuniga walked into the airport hotel, where they were to meet their Cuban counterparts, and "noticed a conspicuous couple sitting at the center of the bar area staring at us — a tattooed man and a woman dressed like an extra in a 1980s Madonna music video," Rhodes writes in his memoir of his time in the White House, "The World As It Is."

President Barack Obama and Ben Rhodes with Cardinal Jamie Ortega at La Catedral de la Virgen Maria de la Concepcion Inmaculada in Old Havana, Cuba, March 20, 2016. White House Photo

The couple walked toward the two US officials as they checked in, stopping just a few feet away. "The man took out an iPhone, held it out in front of him, and took pictures of us," Rhodes writes. "Then they walked off toward the elevators without saying a word."

"Russians," Zuniga said. "Why would they do that?" Rhodes asked.

"They want us to know they're watching," Zuniga told him. "They don't like this."

In December 2014, after 18 months of secret talks, Obama ordered the restoration of full diplomatic relations with Cuba. The push to iron out additional agreements continued. By 2016, officials on both sides were working to get as much done as possible before the end of Obama's term. That year also saw Rhodes' first trip to Havana.

During a tour of the city, Rhodes' group stopped by a statue. "I stood at the base of it until I noticed what appeared to be a few tourists nearby," Rhodes writes, adding that, like in Toronto, the group approached "conspicuously."

"They spoke accented English at first, and then switched to Russian, speaking loud enough to ensure we could hear. None of us acknowledged it."

'I t makes sense ... to lean more on Vladimir Putin'

The talks between the US and Cuba largely focused on settling longstanding issues between them, such as the release of prisoners held by each country, but they took place amid broader geopolitical changes.

A man watches President Barack Obama deliver a speech at the Gran Teatro de la Habana Alicia Alonso in Havana, March 22, 2016. REUTERS/Ivan Alvarado

According to Rhodes, Obama himself expressed displeasure with the Cuba policy he inherited, believing it did nothing to advance human rights and made relations with the rest of the region harder. But his outreach to the region was seen by others as an effort to develop alliances and counter China's and Russia's growing influence there.

Russia's influence around the world, and its support for Cuba, waned after the Cold War. But Vladimir Putin has sought to reestablish Russia as a global power — including building ties in Latin America, such as energy and military partnerships with countries like Cuba, Venezuela, and Nicaragua.

"President Obama's normalization of relations is contrary to Russia's interests because it finally increases US influence in Cuba, whereas Russia was uncontested before," said Greg Weeks, a political-science professor at the University of North Carolina at Charlotte.

Rhodes himself would've been "a natural target for the Russians," Weeks, a Latin America expert, said in an email. Their encounters may have been hints the Russians "might even potentially respond in some manner."

Unexplained injuries suffered by US diplomats in Cuba between 2016 and 2017 have been attributed by some to a third party seeking to goad the US and upend the thaw. Rhodes has said the US was not aware of the attacks when they started in fall 2016 and suggested that rival interests — like Russia or Cuban hardliners — could have carried them out.

Ben Rhodes with then US Commerce Secretary Penny Pritzker and mission chief Jeffrey DeLaurentis in Cuba. Chip Somodevilla/Getty Images

It remains unclear who was behind those attacks, but in mid-2017, President Donald Trump reversed many of Obama's Cuba policies, restricting US travel to the island and prohibiting dealings with the Cuban military, which has sprawling commercial interests. That made dealing with the US harder, but Russia remains a ready partner.

Russia has forgiven 90% of Cuba's Soviet-era debt and backed firms looking to export to the island. In May 2017, Russian state oil company Rosneft began sending fuel to Cuba for the first time in this century. Russian exports to Cuba during the first nine months of 2017 were 81% higher than the same period in 2016. The assistance has been welcomed in Cuba.

"Russia sees it as a moment to further its own relationship with Cuba," Jason Marczak, director of the Atlantic Council's Adrienne Arsht Latin America Center, told Reuters in December. "The more the Russian footprint increases in Cuba, the more that will reinforce hardened anti-US attitudes."

Rhodes has said that Trump curtailing ties with Cuba "delivered a better deal for Vladimir Putin and Xi Jinping."

Trump's moves have also injected more uncertainty at a time of generational political change in Cuba.

Fidel Castro died in late 2016, and Raul Castro left power this spring. Raul's handpicked successor, Miguel Diaz-Canel, took over amid economic struggles and internal debates about reforms. More contentious relations with the US are seen as a complicating factor for the new leader.

"Trump is essentially ceding whatever small influence Obama was developing back to Moscow," Weeks said. "If Miguel Díaz-Canel cannot work with the United States, it makes sense for him to lean more on Vladimir Putin, especially since Venezuela is no longer in a position to assist him."