For the first time, Iran is joining international talks on Syria's future, sending a team to meet with diplomats Friday in Vienna. U.S. Secretary of State John Kerry says he's hopeful about a process that he calls "very difficult."

Much of that difficulty lies in finding a solution to the civil war and humanitarian crisis in Syria that's acceptable to all parties — both within and outside of Syria.

One key decision is what role Syrian President Bashar Assad might play in ending the crisis. He is backed by Iran and Russia, while the U.S. and Saudi Arabia want Assad's rule to end.

Soon after he arrived at the talks in Vienna, Iranian Foreign Minister Mohammad Javad Zarif held meetings with Kerry and with Russian Foreign Minister Sergei Lavrov, according to Iran's state-run media.

"A lot of people see this as the U.S. versus Russia, in the global sphere," NPR's Peter Kenyon reports on Morning Edition. "But the regional rivalry is going to be just as difficult and thorny. The Saudis are really unhappy to see Iran emerging from economic sanctions, getting more power and money as a result of the nuclear agreement. They're really worried that Iran is going to be expanding its influence."

The new round of talks includes countries with regional stakes in Syria's future, from Turkey and Iraq to Lebanon, Egypt, Qatar and Saudi Arabia. The negotiations also include envoys from the U.N., France, Britain and Germany.

There are two notable absences from today's meeting: neither Assad nor the militias who oppose him sent envoys. The sessions are expected to focus on finding areas of possible agreement and compromise.

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