The world is at war, but it is not a war of religions, Pope Francis has said as he traveled to Poland on his first visit to Central and Eastern Europe in the shadow of the slaying of a priest in France.

The killing of an 85-year-old priest in a Normandy church on Tuesday added to security fears surrounding Francis's five-day visit for the World Youth Day celebrations, which were already high due to a string of violent attacks in France and Germany. Polish officials say they have deployed tens of thousands of security officials to cover the event.