A handout picture provided by the office of Iranian President Hassan Rouhani (C) shows him holding hands with Turkish President Recep Tayyip Erodgan (R) and Russian President Vladimir Putin (L) in Tehran on September 7, 2018, as Iran hosted a summit on the Syrian conflict. (Photo by HO / Iranian Presidency / AFP) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / Iranian President's Office" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS
Presidents Hassan Rouhani, centre, Vladimir Putin, left, and Recep Tayyip Erdogan in Tehran. Iran Presidency / AFP

Tehran summit on Syria sees differences over crucial question of Idlib