Last year, he helped to broker an historic accord between Cuba and the United States after half a century of hostility.

This past week, his office announced the first formal accord between the Vatican and the State of Palestine -- a treaty that gives legal weight to the Holy See's longstanding recognition of de-facto Palestinian statehood despite clear Israeli annoyance.

The pope ruffled even more feathers in Turkey last month by referring to the massacre of up to 1.5 million Armenians in the early 20th century as a "genocide", something Ankara denies.

After the inward-looking pontificate of his scholarly predecessor, Pope Benedict, Francis has in some ways returned to the active Vatican diplomacy practiced by the globetrotting Pope John Paul II, widely credited for helping to end the Cold War.