A Syrian rebel and a war monitor said Russian air strikes had resumed against insurgents in Syria's northwestern Idlib province on Tuesday after several weeks.
Syrian President Bashar al-Assad has sworn to recapture every inch of Syria and has made big gains against rebels since Russia joined his war effort in 2015.
Last week, a source close to Damascus said the government was preparing a phased offensive to recover Idlib province, but Turkey, whose army has a string of observation posts around the edge of the rebel area, has warned against such an assault.
Russian air raids ceased in and around Idlib on August 15, but pro-Syrian government forces have maintained an aerial bombardment and shelling against rebels there, the war monitor, the Syrian Observatory for Human Rights, said.
The rebel source and the Observatory both said the air strikes were in the countryside near Jisr al-Shughour on the western edge of the rebels' northwestern territory.
Russian, Turkish and Iranian leaders are due to meet on Sept. 7 in Iran and are expected to discuss the situation in northwestern Syria.