The top diplomats of Russia, Saudi Arabia, Turkey and the United States started key talks on Friday in Vienna to try to find a way to end the Syrian conflict.
Russian Foreign Minister Sergei Lavrov – whose government backs Damascus - was meeting US Secretary of State John Kerry along with the foreign ministers of Turkey and Saudi Arabia, who all support Syrian rebel groups fighting President Bashar al-Assad.
The crunch talks are part of a diplomatic flurry aimed at stopping the conflict in Syria, which has cost more than 250,000 lives over the past four and a half years.
Washington, Riyadh and Ankara are looking to sound out Lavrov after the embattled Syrian strongman made a surprise visit to Moscow to meet President Vladimir Putin this week.
On September 30 Russia launched a bombing campaign in Syria, which has shifted the dynamics of the brutal four-and-a-half year war – allowing Assad's battle-weary forces to go on the offensive and overshadowing a US-led coalition bombing the Islamic State (ISIS) group.
The US and its regional allies have decried Russia's strikes, insisting Moscow is not focusing on ISIS as it claims, but other groups fighting the regime in Damascus, and that the Kremlin's intervention will only prolong the bloodshed.
AFP contributed to this report.