American Airlines announced it is stopping flights to Venezuela because of safety concerns after the pilots’ union told its members to refuse to work the flights. The airline decided to temporarily suspend flights to Caracas and Maracaibo.

“… The safety of our employees and customers is always our top priority and American will not operate to countries not considered safe,” the airline explained in a statement.

American was the last major U.S. carrier to fly to Venezuela, with daily flights to Caracas and Maracaibo from Miami.

Cnnespanol.cnn.com reports that “… the airline said the Corporate Security team is working closely with union leaders to assess the situation in Venezuela. American Airlines flew to Caracas twice a day and to Maracaibo once a day. The three flights this Friday morning have already been canceled,” the press relations department said to CNN.”

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

“Do not travel to Venezuela due to crime, civil unrest, poor health infrastructure, and arbitrary arrest and 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” and call chief pilots, the Allied Pilots Association, which represents about 15,000 American Airlines pilots, said in a note to its members last Thursday.