Pope Francis (R) shakes hands with Cuban President Raul Castro during a private audience at the Vatican on May 10, 2015. Cuban President Raul Castro arrived at the Vatican on Sunday to thank Pope Francis for his role in brokering the rapprochement between Havana and Washington. The first South American pope played a key role in secret negotiations between the United States and Cuba that led to the surprise announcement in December that they would seek to restore diplomatic ties after more than 50 years of tensions. AFP PHOTO/POOL/GREGORIO BORGIA