Cuba
A woman celebrates with people riding in a car and holding posters of the "Cuban Five" in Havana December 17, 2014.Reuters

Pope Francis and the Vatican played a key role in the reopening of U.S. diplomatic relations with Cuba and the release of imprisoned American Alan Gross, senior Obama administration officials said on Wednesday.

The Vatican worked closely with both sides and hosted in-person meetings between Cuban and U.S. officials. Pope Francis, the first Latin-American pope, sent a letter to President Barack Obama and Cuban President Raul Castro urging them to resolve Gross's case and pursue a closer relationship, officials said, speaking on condition of anonymity.

Cuban Cardinal Jaime Ortega also played a significant role in the negotiations for Gross's release, Democratic U.S. Senator Richard Durbin of Illinois told Reuters. Durbin said the talks lasted more than a year.

In March, Obama discussed Cuba with Pope Francis during his visit to the Vatican and has continued to work with the Holy See during the process, an administration official said.

Francis was aware that Obama was considering a change in the policy against Cuba and reached out to the president, the official said, noting that the personal appeal was a rare occurrence that lent greater momentum to the negotiations.

"The support of Pope Francis and the support of the Vatican was important to us," a senior administration official explained, pointing to the Argentine pontiff's history with Latin America. The Obama administration also informed the head of the Roman Catholic Church of the big diplomatic step between the two countries.

"The Vatican welcomed that news," the official noted.

Cuba arrested Gross, now 65, in 2009 and sentenced him to 15 years in prison for importing banned technology and trying to establish clandestine Internet service for Cuban Jews. Gross had been working as a subcontractor for the U.S. Agency for International Development.

"Pope Francis sent letters to President Obama and to Cuban President Raul Castro this past summer urging a resolution of the matter of prisoners and progress in our bilateral relationship," said U.S. Ambassador to the Vatican Kenneth Hackett.

"A senior Vatican official also played an important part in this historic moment by meeting with U.S. and Cuban delegations in October to help bring the negotiations to a successful conclusion," Hackett said.