Among the fruits of this approach have been bilateral agreements on health care cooperation, joint planning to mitigate oil spills and coordination on counternarcotics efforts. Havana also recently agreed to start accepting some Cubans who have been ordered deported. Regulatory changes have made it easier for most Americans to visit Cuba — though going there purely for tourism is still technically illegal — and enabled broader exchanges among scholars, journalists and artists. Google, meanwhile, is negotiating a series of agreements with Cuba that could significantly expand access to the internet on the island, one of the most unplugged nations on earth.

Mr. Trump’s public remarks on Cuba policy have been brief and thoughtless. Shortly after being elected, Mr. Trump tweeted: “If Cuba is unwilling to make a better deal for the Cuban people, the Cuban/American people and the U.S. as a whole, I will terminate deal.”

That put Cubans and Americans on notice that Mr. Trump was contemplating reversing Mr. Obama’s easement of American sanctions. The White House began an assessment early this year and agencies, including the Departments of State, Treasury and Commerce, have given their input. It is unclear when, or whether, an announcement of a decision will come. Mr. Trump could undo many regulatory changes with the stroke of a pen. For instance, he could tighten rules on sending remittances to Cubans, suspend the newly re-established commercial flights between the nations and stop American cruises from docking in Havana.

If he were to take those sorts of steps, Mr. Trump would make the small pro-embargo coalition in Capitol Hill very happy. But doing so would mean reversing course on a policy change that is widely popular among Americans and nearly universally supported by Cubans.

He also would be putting American farmers and businesses at a disadvantage by curtailing their access to a market that is gradually opening to global trade. In 2016, the European Union formally abandoned a policy predicated on pursuit of a democratic transition and struck a broader agreement with Havana that includes cooperation on trade and development and a dialogue on human rights.