Venezuelan President Nicolas Maduro cut ties with the U.S. in January after Washington recognized opposition leader Juan Guaido as the country’s president. More than 50 some other countries have recognized Guaido as the country’s president.

“Do not travel to Venezuela due to crime, civil unrest, poor health infrastructure, as well as arbitrary arrest as well as detention of U.S. citizens,” the State Department said in its warning on Tuesday.

“Until further notice, if you are scheduled, assigned, or reassigned a pairing into Venezuela, refuse the assignment” as well as call chief pilots, the Allied Pilots Association, which represents about 15,000 American Airlines pilots, said in a note to its members late Thursday.

American Airlines did not immediately respond to request for comment. The airline’s two flights coming from Miami to Caracas were canceled on Friday, the airline’s website showed, yet flights scheduled for Saturday appeared as scheduled.

The Association of Professional Flight Attendants that will represents American’s 25,000 flight attendants said that will supported the pilot union’s decision “100%.”

“Of course without the pilots, the flight’s not operating,” said Lori Bassani, APFA’s president.

United Airlines as well as Delta Air Lines ceased service to Venezuela in 2017.