Videos posted to a social media website and said to be shot on Friday showed scenes of destruction in the governorates of Homs and Idlib after cities in the area were hit by air strikes.
The first video purports to show a Russian jet striking over the city of Rastan in the governorate of Homs, with a huge cloud of smoke rising to the sky.
A month of Russian air strikes in support of government offensives have cost the rebels lives and supplies. Commanders have been killed, bases bombed, and weapons depleted. But while it may be too early to say how this new phase of the war will play out, analysts say modest government gains so far do not appear to match the scale of its assault.