WASHINGTON (AP) — The U.S. is imposing visa restrictions on Cuban officials involved in a program that sends doctors around the world.

Secretary of State Mike Pompeo says the program forces Cuban medical professionals to work long hours and live in unsafe areas while advancing what he calls the Cuban government’s “political agenda.”

He did not disclose the number of officials or identify them.

Cuba has sent doctors around the world for decades. The doctors have helped many people in countries where medicine is scarce, but the program is also a source of income for the Cuban government.

Relations between the U.S. and Cuba have deteriorated under President Donald Trump in part because of Cuban support for the embattled president of Venezuela.

The Cuban government had no immediate comment on Pompeo’s announcement Friday.