VATICAN CITY — (CNN) The leader of the Roman Catholic Church and the President of Iran met Tuesday at the Vatican, a face-to-face encounter that speaks to a changing geopolitical landscape and both men’s significant role in it.

Cameras captured Pope Francis and President Hassan Rouhani shaking hands and sitting down across from each other. No details were immediately available about exactly what they discussed.

No doubt, though, they have a lot to talk about — from the bloody, years-long war and humanitarian crisis in Syria to endangered Christians in the Middle East to the increasing integration of the country officially called the Islamic Republic of Iran into world affairs following the striking of a landmark nuclear deal.

“I think that the meeting of President Rouhani with the Pope is one of the signals of the fact that, after the nuclear deal, we have a possibility of a relevant involvement of Iran in a regional and global framework,” Italian Foreign Minister Paolo Gentiloni told CNN’s Christiane Amanpour.

The pair — one a senior Muslim cleric, the other the world’s most recognized Christian leader — had planned to sit down in November, according to official Iranian and Vatican news outlets. But Rouhani postponed that meeting, and his entire trip to Europe, following that month’s coordinated terrorist massacre in Paris.

Since then, Tehran has celebrated the lifting of sanctions after international authorities found it in compliance with steps restricting its nuclear program. Rouhani had championed that nuclear deal since his 2013 election, seeing it as important to bringing Iran more into the fold internationally.

Economics played a big part in Rouhani’s push, and in his European trip. To that end, prior to the Vatican meeting, Italian and Iranian officials signed billions of dollars in trade deals that Gentiloni says mark “a new era in economic relations.”

One topic that’s now less of an issue: Iran’s holding of American prisoners like Saeed Abedini, an Iranian-born pastor who later immigrated to Idaho. After appeals for the Pope to intervene, Abedini and four others were freed earlier this month.

It’s highly unlikely business was high on the agenda for Pope Francis. The Catholic leader has been a top worldwide figure on many issues — leadership that led Time magazine to name him its 2013 Person of the Year — that would be relevant in a sit-down with Rouhani, Syria likely foremost among them.

Francis has persistently called for peace and opposed widening military interventions in Syria, even making the message a focus on his first Christmas as Pope. In response, and in apparent recognition of the Pope’s high moral standing worldwide, embattled Syrian President Bashar al-Assad sent a message of appreciation for Francis’ words and his support for a peaceful resolution “through national dialogue.”

Yet little has changed since then in Syria. If anything, things seem to have gotten worse. U.N. envoy Staffan de Mistura said this month that the war has left more than 220,000 people dead, 1 million wounded, 3.3 million as refugees, 7.6 million internally displaced and 12 million total in need.

Iran has been one of Assad’s few allies, though it’s largely been on the sidelines in international efforts to broker some sort of peace. Increasing openness to Tehran may mean a new role for Rouhani and other officials and perhaps contribute to a breakthrough.

The latest round of Syria peace talks were set to begin Monday in Geneva, Switzerland, only to be delayed due to ongoing discussions about who should represent the Syrian opposition, de Mistura said. Both U.S. Secretary of State John Kerry and his Russian counterpart, Sergey Lavrov, have publicly urged talks as soon as possible — though the fact there’s not even agreement on who should talk speaks to how complex, convoluted and emotionally charged this conflict is.

Gentiloni, the Italian foreign minister, expressed hope that Iran’s increasing engagement could be pivotal in what happens in Syria.

“I think that diplomacy made a little miracle with the nuclear deal,” he said. “We need, now, perhaps a second one … I think that Iran should be involved.”

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