Gregory Korte, and Oren Dorell

USA TODAY

WASHINGTON — A personal appeal by Pope Francis played a key role in finalizing a deal to open relations between the United States and Cuba for the first time in 53 years.

The pope wrote a personal letter to President Obama this fall — something he'd never done before — and a separate letter to Cuban President Raúl Castro.

The letter invited the leaders to "resolve humanitarian questions of common interest, including the situation of certain prisoners," according to a Vatican statement congratulating the two countries Wednesday. The Vatican said it received delegations from both countries in October and helped facilitate a dialogue.

That resulted in a major U.S. policy shift toward Cuba, including a prisoner swap between the two countries that freed American Alan Gross on Wednesday.

"The Holy See will continue to assure its support for initiatives which both nations will undertake to strengthen their bilateral relations and promote the well-being of their respective citizens," the statement said.

In addition to the Vatican meeting this fall, discussions between the two leaders took place in Canada over the past year and a half, according to a senior administration official who spoke on condition of anonymity because he was not authorized to discuss the talks publicly.

Aside from President Obama and the Cuban president, the pontiff was the only other foreign leader directly involved in the talks, the official said.

Francis' support was particularly important given Cuba's historical and cultural Catholic identity, the official said, and his election as the first-ever pope from Latin America gave him credibility.

Before he was Pope Francis, the Argentinian served as Bishop of Buenos Aires, where he was a prominent member of the Episcopal Conferences of Latin America. That group, along with the Vatican and U.S. Conference of Catholic Bishops, has long advocated for normalized relations between the United States and Cuba.

Their rationale "stems from the Vatican's long-standing desire to overcome conflictual divisions between nations," said Stephen Schneck, who works at the Catholic University of America. "It's very much part of the pope's own understanding of proper foreign relations."

In addition, the Latin American bishops believe residents in the hemisphere should be doing business with each other and getting along, Schneck said.

"(They've) seen this split between the United States and Cuba as a kind of split among American brothers," he said.

Dorell reported from McLean, Va.