This hard-line sanctions-based approach was in place for more than 50 years after the 1959 revolution and never produced what anti-Castro activists hoped would be the result, the ouster of Cuba’s Communist government in favor of democracy. Isolating Cuba has become increasingly indefensible.

Mr. Obama’s opening to Havana has enabled the freer flow of people, goods and information between the two countries, even as significant differences remain over human rights. It has produced bilateral agreements on health care cooperation, joint planning to mitigate oil spills, coordination on counternarcotics efforts and intelligence-sharing. In April, Google’s servers went live in Cuba and thus it became the first foreign internet company to host content in one of the most unplugged nations on earth. Mr. Obama’s approach also encouraged Latin American countries to be more receptive to the United States as a partner in regional problem-solving.

A large pro-engagement coalition that includes lawmakers from both parties, businesses and young Cuban-Americans is pushing the White House to build on the foundation of engagement it inherited from Mr. Obama, not tear it down. Engage Cuba, representing business groups, economists and leading Cuba experts, has estimated that a reversal of Mr. Obama’s policies would cost the American economy $6.6 billion and affect more than 12,000 American jobs.

The group predicts that the hardest-hit areas will be rural communities that rely on agriculture, manufacturing and shipping industries, as well as Florida, Louisiana, Texas, Alabama, Georgia and Mississippi, all of which supported Mr. Trump in the 2016 election. Among the deals that could be squashed is one struck by Starwood Hotels and Resorts last year to manage hotels in Cuba; future ones would effectively be frozen.

The White House and its allies argue that the Cuban government remains despotic and must be pressured to reform. But pressure has had a minimal impact and the human rights concerns are disingenuous, given Mr. Trump’s effusive embrace of authoritarian leaders from President Vladimir Putin in Russia to President Abdel Fattah el-Sisi in Egypt. He also pointedly told Sunni Arab leaders in Saudi Arabia last month that he has no intention of lecturing them on their repressive behavior toward their citizens.