A meeting between the Turkish and Iranian presidents has started in the Russian coastal city of Sochi.
The one-on-one meeting of Turkey's Recep Tayyip Erdoğan and Hassan Rouhani comes just ahead of Thursday's trilateral summit on Syria of Turkey, Russia, and Iran.
Erdoğan, Rouhani, and Russian President Vladimir Putin will meet to discuss joint efforts on the ground and as part of the political process by the Astana platform to find a lasting solution to the Syrian conflict.
The leaders first met to discuss Syria in Sochi in 2017.
Turkey, Russia, and Iran are guarantor countries which brokered a cease-fire in Syria in December 2016, leading to the Astana talks, which are running parallel to the Geneva talks.
Syria has been locked in a vicious civil war since early 2011, when the Assad regime cracked down on protesters with unexpected ferocity.
Since then, hundreds of thousands of people are believed to have been killed and millions more displaced by the conflict.
Before leaving for Sochi, Rouhani told reporters at Tehran's Mehrabad International Airport that some oil-rich countries in the region support terrorism.
"The U.S. and Israel are the paths for terrorism in our region," Rouhani said. "Unfortunately, some oil-rich countries in the region support these terrorists."
On the U.S. military withdrawal from Syria, he said it was good news if true, arguing that the U.S. "occupying force" being in the country violates international agreements.
