The U.S. border czar has pushed back against Pope Francis' criticism of the U.S. mass deportation of migrants plan.

In a letter to American bishops, Francis leveled unusually direct criticism at the administration on an issue he has made central to his papacy.

In the letter, the pope said the criminalization of migrants and the mass deportations planned by the U.S. government are dangerous and called the country's current immigration policies a “major crisis.