Damascus says it is waging a war against al Qaeda-inspired terrorists and denies targeting civilians indiscriminately.
Last week witnesses and rescuers said that Russian jets bombed villages and towns near Idlib, killing at least nine civilians and wounding dozens in a major flare-up.
Russia appeared weak as it faced internal chaos. This could be a reason for these new rounds of airstrikes.
Russia maintains a significant military presence in Syria and has been a close ally of Assad.