11 And secondly, We are aware - to the great sorrow of Our fatherly heart - that the Catholic Church, in both its Latin and Oriental rites, is beset in many lands by such persecutions that the clergy and faithful, if not in so many words, certainly in fact, are confronted with this dilemma: to give up public profession and propagation of their faith, or to suffer penalties, even very serious ones. As a result, many bishops have been driven from their sees or so impeded that they cannot freely exercise their ministry; they have even been cast into prison or exiled. And so with rash daring men undertake to fulfill the words: "I will smite the shepherd, and the sheep of the flock will be scattered."
Source: Meminisse Iuvat (Vatican.va)