CNN  — 

Delicately dancing around centuries of theological tensions, Pope Francis and Russian Orthodox Patriarch Kirill met in Cuba on Friday and pleaded for world leaders to protect persecuted Christians.

“Thousands of victims have already been claimed in the violence in Syria and Iraq, which has left many other millions without a home or means of sustenance,” the Pope and patriarch said in a joint declaration.

“We urge the international community to seek an end to the violence and terrorism and, at the same time, to contribute through dialogue to a swift return to civil peace.”

The meeting, which took place at Jose Marti International Airport in Havana, was the first encounter between a pope and a Russian Orthodox patriarch.

“Finally!” Francis exclaimed in Spanish upon meeting Kirill, embracing his fellow Christian leader. “We are brothers.”

In their joint declaration, the Pope and patriarch touted their historic conclave as an “indispensable” example of civility for a world riven by violence, poverty and sectarian strife.

“In a world which yearns not only for our words but also for tangible gestures, may this meeting be a sign of hope for all people of goodwill!”

The meeting is a diplomatic victory for Francis, who has made door-opening dialogue a prominent feature of his foreign policy. But it also carries some risks. Critics have warned that Kirill and Russian President Vladimir Putin, who are close, will use the Pope to boost their profile among Orthodox Christians and popularity in the West.

“The meeting takes place against the backdrop of current Russian military, political, and propagandist actions,” said Yury Avvakumov, assistant professor of theology at the University of Notre Dame. “At this moment, it would be useful for Russian leaders to have any public figure who would approach Russia with a ‘business as usual’ attitude.”

Still, many Catholics and Orthodox Christians hailed the meeting and joint declaration as significant steps toward strengthening ties between their traditions, which separated in 1054 after the Great Schism. (Also called the East-West Schism, the split was over theology and the primacy of the pope, whom the Orthodox do not consider the supreme leader of Christianity.)

Patriarch Kirill is not the leader of Orthodox Christianity, a title that technically belongs to Ecumenical Patriarch Bartholomew, who is based in Constantinople and has met with Pope Francis and his predecessors several times. But with a flock of 150 million followers, Kirill leads the biggest, and in some ways the most defiant, branch of Orthodoxy.

The Vatican had tried for decades to meet with Russian patriarchs, amplifying their efforts after the fall of the Soviet Union in the 1990s. But Orthodox leaders accused Catholics of trying to encroach on their turf by planting new churches in Russia and former Soviet satellite countries.

Friday’s joint declaration delicately alludes to the tensions between the churches, noting that Orthodox Christians and Catholics “have been divided by wounds caused by old and recent conflicts.” But the Pope and patriarch said they were “pained by the loss of unity” among Christians, who have splintered into thousands of denominations since the schism in 1054.

Despite their differences, the vicious persecution of Christians in the Middle East and Africa by the Islamic State and other terrorists reportedly prompted the Russians to consider meeting with their Catholic counterparts.

Christian persecution reached record high in 2015, report says

“We need to put aside internal disagreements at this tragic time and join efforts to save Christians in the regions where they are subject to the most atrocious persecution,” senior Orthodox cleric Metropolitan Hilarion told reporters.

Pope Francis has also argued that Christians should come together to protect their persecuted brethren, calling it an “ecumenism of blood.”

While pledging not to proselytize – a fancy word for stealing converts from other faiths – Francis and Kirill said they are determined to “undertake all that is necessary to overcome the historical divergences we have inherited.”

“We are not competitors but brothers, and this concept must guide all our mutual actions as well as those directed to the outside world.”

Since his election in 2013, Francis has made concerted efforts to heal the breach between Catholics and Russian Orthodox Christians, telling Kirill in 2014: “I’ll go wherever you want. You call me and I’ll go.”

Both sides apparently consider Cuba neutral ground. Kirill is there for an official visit; Francis flew to Mexico, where he will spend five days. He received an exuberant and festive welcome Friday evening.

In a possible preview of the Pope’s agenda in Mexico, where he will celebrate Mass near the U.S. border in Juarez, Friday’s joint declaration states:

“We cannot remain indifferent to the destinies of millions of migrants and refugees knocking on the doors of wealthy nations.”

The Pope, the Donald, and the wall between them

The historic meeting between Pope and patriarch came less than a year after Francis’ first visit to Cuba as Pope. He played a key role in the recent thawing of relations between the United States and Cuba, which re-established diplomatic ties last year.

Richard Greene contributed to this report.