U.S.-operated cruises and scheduled flights to the Caribbean island were relaunched last year after a half-century hiatus, as part of the detente with Cuba pursued by former President Barack Obama.

That may be under threat as U.S. President Donald Trump's administration considers reinstating some of the restrictions on travel and trade eased by Obama as it prepares to roll out a new Cuba policy as early as this month.

"Rolling back expanded travel will cost airlines $512 million annually ... based on the average ticket fare," Engage Cuba wrote in the report to which a host of Cuba experts contributed.

U.S. airlines flying to Cuba include JetBlue (>> JetBlue Airways Corporation), American (>> American Airlines Group Inc), Delta (>> Delta Air Lines, Inc.) and Alaska.

Cruise operators, from Carnival (>> Carnival Corp) to Norwegian (>> Norwegian Cruise Line Holdings Ltd), stand to lose $200 million in revenue per year, Engage Cuba estimated, noting thousands of jobs in both sectors were at risk. The estimate was based on lost revenue from fully booked flights and cruises.

Eliminating cruises to Cuba could also cost South Florida's economy an additional $212.8 million, given what passengers spend in port communities, Cuba Engage said.

The study likely overestimates the economic impact of a rollback, some Cuba experts said, as Trump is not expected to unravel the entire detente.

"First, tightening regulations does not mean severing completely certain U.S.-Cuba economic ties," said Paolo Spadoni, Associate Professor of Political Science at Augusta University.

"Second, what about the gains of charter companies if commercial flights are discontinued?"

Supporters of the U.S.-Cuban detente are stepping up their lobbying to influence the Trump administration review.

A bipartisan group of U.S. senators last week reintroduced legislation to repeal all restrictions on travel to Cuba, this time attracting far more co-sponsors.

U.S. tourism to Cuba is still not allowed, but Obama's decision to ease travel restrictions fueled a boom in American visitors under categories like educational travel. The number of U.S. visitors rose 74 percent last year.

(Reporting by Sarah Marsh in Havana and Matt Spetalnick in Washington; Editing by Richard Chang and Chris Reese)

By Sarah Marsh and Matt Spetalnick