ROME — In a historic move, Pope Francis will meet the head of the Russian Orthodox Church, Patriarch Kirill, Feb. 12 in Cuba as the pontiff is on his way to Mexico.

The meeting, the first between a sitting pope and a Russian patriarch, will be an important step in mending the Great Schism that divided Eastern and Western Christianity in 1054.

“This meeting of the Primates of the Catholic Church and the Russian Orthodox Church, after a long preparation … will mark an important stage in relations between the two Churches,” said a joint statement released by both churches Friday.

The encounter between the two leaders, expected to last roughly two hours, will take place at Jose Marti International Airport in Havana, and will conclude with the signing of a joint declaration. No details about the content of that agreement were released.

Kirill will be visiting the island nation as part of his first-ever official visit as patriarch of the Russian Church to Latin America. His tour will include stops in Brazil and Paraguay.

According to a Vatican spokesman, Francis will be welcomed in Cuba by President Raúl Castro. It will mark a return engagement in Cuba for Francis, who made a three-day pastoral visit in September 2015 before his trip to the United States.

The Rev. Federico Lombardi, the Vatican spokesman, said the stop in Cuba will force the pope to leave Rome earlier on Feb. 12, but it will not change the pope’s Mexico schedule. He’s expected to arrive at the Mexican capital in late afternoon, and beyond an informal reception at the airport, there are no official activities scheduled.

Metropolitan Illarion, foreign policy chief of the Russian Orthodox Church, told reporters on Friday that there are still core disagreements between the Holy See and the Russian Church, in particular on various Orthodox churches in western Ukraine.

Nonetheless, the two churches have found common ground in the persecution of Christians in several regions of the world.

“The situation in the Middle East, in northern and central Africa, and in other regions where extremists are perpetrating a genocide of Christians requires immediate action and an even closer cooperation between Christian churches,” Illarion said. “In this tragic situation, we need to put aside internal disagreements and pool efforts to save Christianity in the regions where it is subject to most severe persecution.”

The Vatican has long nurtured ties with the Istanbul-based Ecumenical Patriarch, Bartholomew I, who is considered “first among equals” within the Orthodox Church. Starting with Pope Paul VI, various popes have called upon the Ecumenical Patriarch in hopes of bridging closer ties with the Orthodox faithful.

But the Russian Orthodox Church, which is the largest church in Orthodoxy and the most powerful, has always kept its distance from Rome. Joint theological commissions have met over the years, and the Russian church’s foreign minister has made periodic visits to Rome, but a pope-patriarch meeting has never been possible until now.

From the beginning, Lombardi said, such a summit had to be in a neutral place.

“Cuba is a place well-known for the Russian Church,” Lombardi said. “And three popes visited the island, so it made sense.”

The Vatican spokesman described Kirill as heavily invested in ecumenism. Before becoming patriarch, he was the official within the Russian Orthodox Church in charge of the rapport with other churches.

“The exceptional aspect of this meeting is that it’ll be the first one,” Lombardi said. “It’s an event that on the path of ecumenism has an extraordinary importance.”

Both St. John Paul II and emeritus Pope Benedict XVI tried holding this meeting in Moscow, but it never came to be. One obstacle was the belief by Russian religious leaders that the Catholic Church was trying to convert Orthodox faithful in what Orthodox leaders considered their territory.

Yet a study in 2002 found there were just 800 conversions in the entire decade of the 1990s. Meanwhile, Evangelical and Pentecostal Christianity exploded in Russia, so much so that a 2012 book referred to it as a “post-Soviet gold rush.”

In the 2000s, in another sign of appeasement, the Vatican imposed an informal “no-growth” policy, instructing pastors to tell any Russian who wanted to become Catholic to go back to their Orthodox parish.

Far from expanding, Catholicism shrunk, in part because many ethnic Germans and Poles left Russia.

The Russian Orthodox have also consistently vetoed a papal trip to the country, making Moscow one of just a handful of places, including Beijing and Pyongyang, where the pope is not welcome.

Archbishop Georg Gänswein, the personal secretary of emeritus Pope Benedict XVI, told reporters on Friday that the retired pontiff was informed of the upcoming meeting, saying Benedict called it a “historic encounter, a historic step.”

Gänswein said Benedict and Kirill know each other well from when the future pope was still the Vatican’s top doctrinal official, and the Russian Orthodox cleric was a metropolitan. According to Gänswein, one of Benedict’s first meetings after his election to the papacy was with Kirill at the Domus Santa Marta, the hotel where Francis now lives.

Benedict helped lay the groundwork for the upcoming meeting, Gänswein said, adding that by adding new “columns” and “pillars,” Francis has helped “build the house.”

Francis voiced his skepticism over the viability of this meeting in 2014, listing the war in eastern Ukraine and theological differences, though he said both he and Patriarch Kirill wanted to meet.

“I said, ‘I’ll go wherever you want — you call me and I’ll go.’ And he also has the same desire,” Francis said in 2014, in response to a reporter’s question while flying from Turkey back to Rome. “But with the problems of the war, the poor guy has so many problems, so a meeting with the pope will have to wait.”

Francis also said such meeting would need to wait “until the theologians agree among themselves.”

(The two sides have theological differences that date to 1054, when the two churches split. Catholics insist on the primacy of the pope of Rome, while the Orthodox Church is less centralized.)

“We’ll never get to that day, I assure you,” Francis said then. “I am skeptical.”

Not anymore.

Material from the Associated Press was used in this report.