By: Will Grant
Five days of military exercises were scheduled to take place across the island this month, said the state-run newspaper, Granma, as Cuba's armed forces readied themselves for "a range of enemy actions".
In reality, those exercises take place every few years and, by the end of the day, President Raul Castro had sent his formal congratulations to Mr Trump, who will take office in the wake of last year's re-establishment of ties between Havana and Washington.
Even that brief congratulatory message represents an important break with the past.
Quite what the 85-year-old communist leader makes of the former reality TV star isn't clear. He has seen 10 US presidents come and go since he and his brother, Fidel, took power in 1959, some of them vehemently opposed to the Castro government and intent on forcing them from office.
Raul Castro is unlikely to have dealt with a US political figure quite like Donald J Trump.
The extraordinary mixture of braggadocio and brash populism is more often compared with a very different Latin American leader: the late Venezuelan President, Hugo Chavez.
Beyond their personal differences, though, it is Mr Trump's position on the much-vaunted process of thaw that is most under scrutiny in Cuba at this stage. Early in his campaign he said he was "fine" with the Obama administration's policy of rapprochement.
"Fifty years is enough time, folks," he said during a CNN televised debate.
Rolling back detente?
However, by the end of the arduous campaign, he was in Little Havana in Miami, drinking coffee with Cuban-American opponents of the thaw in the well-known Cafe Versailles.
He promised anti-Castro Republicans that he would roll back on Mr Obama's detente, would keep the decades-long US economic embargo on the island firmly in place and would even close the recently reopened US embassy in Havana.
"I want to believe that this was last-minute election opportunism, a kind of old-style form of it and one which I don't think benefited him that much," says Mike Bustamante, an assistant professor in Latin American history at Florida International University.
Certainly it didn't seem to make a huge difference at the polls, as Hillary Clinton got roughly the same percentage of the Cuban vote in Florida as Barack Obama did in 2012.
"It's hard to say whether he's genuinely planning to implement these policies. Let's not forget that a number of years ago representatives of his companies violated the embargo by coming out and scouting out investment opportunities in Cuba," says Dr Bustamante, referring to an article in Newsweek magazine which alleges that Trump executives visited Cuba in 1998.
His campaign argued that the story simply showed he didn't invest any money on the island.
Still, if he approaches the issue as a hotel businessman, President Trump might actually prove more favourable to lifting the embargo than he led his audience in South Florida to believe.
Dr Bustamante is less concerned about what a Trump administration would do in the short-term than seeing both houses of Congress and the White House in Republican hands.
"If folks in Congress who oppose the normalisation add an amendment to a bill that strips away a piece [of the detente], would a Trump White House threaten a veto?" he asks rhetorically.
However, one of the key lobby groups pushing for greater engagement with Cuba actually believes the latest make up of the House and the Senate could work in their favour.
"On Tuesday night, the pro-engagement forces picked up four senators and over 10 pro-engagement members in the House," says James Williams, president of the "Engage Cuba" advocacy group in Washington DC.
"We came into this in a strong position, but we're actually in a much stronger position than we were a few days ago."
The last time he eased the economic embargo, Mr Obama called his administration's steps towards Cuba "irreversible". But many are based on executive orders and, when president, Mr Trump could repeal them.
James Williams doubts he will. "This is one of the single-most popular policy decisions in the country. We had a poll that showed 63% of Cuban-Americans in Miami want to see the embargo lifted. So the only conclusion to draw is that it should continue to move forward."
Meanwhile, in Havana, the mood is a mixture of uncertainty and stoicism.
"It's terrible news," says Angel Bacallao, a retired state employee. "He said he'd turn to ashes all the steps that Obama has made towards better relations with the US. He'll get rid of them all."
Others noted that Cuba has been through difficulties with Washington many times before.
"We have to wait and see what he's like," says Jose, a private business owner. "He's very unpredictable."
Some in Cuba suggest a Trump presidency might even be welcomed by hardliners who oppose the rapprochement.
"We don't need the empire to give us any presents," Fidel Castro wrote shortly after President Obama's landmark visit.
After all, it's easier to rally people against a traditional enemy than one bearing gifts.