US President Donald Trump moved to roll back some of his predecessor’s policy of reopening relations with Cuba, but Trump will keep the air services pact in place that allows commercial flights between the two countries.

However, Trump said the US government will “strictly” enforce the ban on US tourism in Cuba. In particular, “people-to-people” travel—which allowed individuals to travel to Cuba on approved trips—will be eliminated.

Nine US airlines launched flights to Cuba in the second half of 2016 and early 2017 after President Barack Obama eased longstanding tensions with Cuba and agreed to a new air services accord restarting scheduled commercial flights between the US and Cuba for the first time in over 50 years. But three US airlines have already pulled out of the market, which has proved difficult for US carriers. Overcapacity is an issue, compounded by the prohibition on US citizens traveling to Cuba purely for a vacation. The elimination of people-to-people trips, and requiring that Americans only travel to Cuba as part of certified groups, will likely place another strain on the US-to-Cuba air transport market.

A senior administration official told reporters in a background briefing at the White House that “the requirement is that individuals who are going to Cuba actually engage in a full-time schedule of activities designed to enhance their interaction with the Cuban people and … consistent with the policy objectives of ensuring that the money [they spend] goes to the Cuban people and not to the military [or] intelligence services.”

The US Treasury Department will have to write new regulations so US citizens flying to Cuba in the coming days will not be affected. “None of the changes will go into effect until the regulations are issued,” the administration official said. “One of the things that the Treasury Department will cover in its regulations is how individuals who have started planning travel to Cuba, but have not actually completed that travel, will be affected.”

A spokesperson for Airlines for America (A4A) said in an emailed statement: “Airlines are reviewing the president’s directive and will continue to comply with all federal rules and regulations regarding travel to Cuba. US airlines connect the world like no other industry can and we remain committed to advocating for policies that enable carriers to facilitate travel and trade, and increase access to more markets and destinations globally.”

Trump said the US embassy in Cuba, reopened by the Obama administration, will remain open. But he indicated that his policy toward Cuba will not change while Raul Castro remains the island nation’s president, calling for “free and internationally supervised elections” to be scheduled in Cuba.

Aaron Karp