A summit between the presidents of Turkey, Russia and Iran may determine whether diplomacy halts any military action in Syria's last rebel and opposition-held province. Presidents Erdogan, Putin and Rouhani are now in Tehran ahead of the talks.
The leaders of Turkey, Russia and Iran are due to meet on Friday in Iran. They're expected to discuss northwestern Syria's Idlib where the regime is reported to be planning an imminent offensive against remaining opposition and rebel-held areas.