Russian officials said long-range bombers hit Islamic State targets (IS) in the group's de facto capital of Raqqa, as fierce fighting continued in the besieged city of Aleppo.
The fighting in Aleppo -- once Syria's largest city-- came despite a promised Russian aid window the United Nations said was insufficient to bring relief to the city's desperate residents.
The Russian airstrikes around Raqqa on August 11 killed at least 20 civilians, Syrian activists said, and came amid Turkish calls for greater cooperation with Moscow against the extremist group.
During a visit to Russia earlier this week, Turkish President Recep Tayyip Erdogan and his Russian counterpart, Vladimir Putin, agreed to coordinate more closely in the fight in Syria.
Turkish Foreign Minister Mevlut Cavusoglu said Turkey would resume air strikes against Islamic State targets in Syria, months after they were suspended amid the row with Moscow over Turkey's downing of a Russian jet.
In Aleppo, a Syrian rescue worker and opposition activists said on August 11 that a Syrian government air strike on an opposition-held district in the embattled city killed at least two people.
The attack on the city's eastern Zabadieh neighborhood saw at least four barrel bombs dropped on the area, one of which purportedly released chlorine gas.
Since erupting in March 2011, Syria's conflict has mutated into a brutal civil war that has killed more than 290,000 people and displaced more than a million.