The thaw was hailed by many as a turning point in relations between the two countries, which had remained frozen in a Cold War-era standoff.
But looking back on the optimism of December 17, 2014, analysts now say the effects of the milestone agreement have been curtailed by the administration of US President Donald Trump and the spillover from the crises in Venezuela.
Under the landmark deal, announced by then-presidents Barack Obama and Raul Castro after months of secret talks, embassies were reopened, prisoners exchanged and restrictions on tourism to Cuba relaxed.
In the years since, the agreement has languished, weathering numerous rollbacks and sluggish implementation of some of its promises.
Under the Trump administration, which has directed a near about-turn in US foreign policy towards Cuba, limits on tourism have been reimposed and a harsher policy towards Cuban migrants and refugees adopted.
In the last week, Cuba’s top diplomat told AFP news agency that Havana is bracing for the possibility that Washington might completely sever relations once again, effectively erasing all tangible traces of the deal.
“For various reasons, the Trump administration has decided, as it has done with so many policies implemented by President Obama, that it wants to do the opposite,” James Mahon, a professor of political science at Williams College, Massachusetts, told Al Jazeera.
Washington has piled pressure on Havana on several fronts; passing legislation to block US cruise ships from docking in the Cuban capital and halting all flights to the island’s other airports.
“I just got back and I noticed a really drastic change,” Carlos Seiglie, a professor of economics at Rutgers University said, adding that Havana’s residents appeared “depressed” by the reversal of fortunes.
“The restrictions on cruise ships being able to dock in Havana [has] really destroyed the taxis, the food [sellers], the individuals who sold little souvenirs, the markets that sold souvenirs are just empty and that wasn’t the case a year ago,” he told Al Jazeera.
A key factor driving the Trump administration’s more hostile approach to Cuba is the desire to appeal to largely-Republican Cuban American voters in the key swing state of Florida, Mahon said.
The 2014 deal is extremely unpopular among the influential community, many of whose families fled persecution in Cuba under former leader Fidel Castro. Activists and Republicans have criticised the agreement for making too many concessions to Cuba without reciprocal efforts by the one-party state to liberalise its economy or improve human rights protections.
“There are many Cuban Americans in the Miami metropolitan area who will vote entirely on the basis of Cuba policy,” Mahon told Al Jazeera.
Cuba’s human rights record is frequently cited by critics of the deal and has long been a stumbling block for improving relations with the US.
The appointment of Miguel Diaz-Canel as president in April 2018 and the announcement of a constitutional referendum held earlier this year prompted some hopes of reform, which rights groups say have largely been dashed.
“It was the first time in many decades that the country had a president born after the 1959 Revolution. There was some hope that change could be possible […] However, 18 months later, nothing has changed,” said Erika Guevara-Rosas, Americas director at Amnesty International, which is barred by Havana from doing work on the island. Several other independent rights organisations are also banned.
“We have documented the continued detention, harassment and intimidation of human rights defenders, political activists and independent journalists. Those who peacefully protest or express even subtle criticism of the government’s political or economic model are frequently targeted,” Guevara-Rosas told Al Jazeera. “For many Cubans, significant structural change to the human rights situation in Cuba is inconceivable any time soon.”
However, Mahon said human rights were a “secondary concern” for the Trump administration, saying cementing support in Florida and affecting regime change in Venezuela were more pressing.
“I would put human rights way down the list of concerns for the current US government,” he said. “If there were a state somewhere that had lots of refugees or exiles from North Korea and that state were as big as Florida and it were a swing state, Donald Trump would not be negotiating anything with North Korea.”
A US State Department official told Reuters news agency this week that there were “no plans to break off diplomatic ties” with Havana, but “one thing that has clearly reached a low point is the Castro regime’s abuses of its own people”.
“In addition, the regime is spreading its totalitarian repression to other countries in the region,” the official added, speaking to the news agency on the condition of anonymity.
Perhaps nowhere is this more evident than in Venezuela where the US has thrown its support behind opposition leader and self-declared interim President Juan Guaido.
The effect of the political, economic and social crises in Venezuela is being strongly-felt in Cuba as the economic collapse of its longtime regional ally has put further strain on the Caribbean island’s crumbling economy – already under severe pressure from a decades-long US embargo.
Venezuela is less able to supply Cuba with cheap, subsidised oil, creating a fuel crisis on the island where long lines for petrol and public transport have become a fixture in the last year.
Meanwhile, the Communist Party’s continued support for Venezuelan President Nicolas Maduro has seen the US recast Cuba as an antagonist in regional affairs.
“The US policy towards Venezuela has become openly hostile to the current regime and wants to engine a change of regime and that has put it at odds with Cuba directly,” Mahon told Al Jazeera.
In September, the US announced that the amount of money Cubans in the US can send to families at home in remittances has been slashed, which Sieglie said has had an “enormous” effect on the lives of Cubans.
He added that these new waves of sanctions, on top of the already-crippling embargo, could indeed result in diplomatic relations between the US and Cuba breaking down entirely.
“I hope that’s not the case, but it is quite a possibility,” he said. “There is an entirely different focus now with this administration on really containing Cuba and doing similarly to Venezuela. I think the impact has been really profound.”
Follow Charlotte Mitchell on Twitter: @charbrowmitch