Syrian regime warplanes struck rebel-held Eastern Ghouta suburbs near the capital on Monday, despite Safe Zone deal that reached with Russia two days ago, local activists said.
The airstrikes hit towns of Douma, Harasta, Housh al-Dhwahra and Eiyn Tarma, leaving several people wounded and huge destruction.
Russia deployed its military police in the Eastern Ghouta on Monday to try to enforce a de-escalation zone it said it had agreed with the opposition, Reuters reported.
The regime military declared a cessation of hostilities on Saturday in the rebel-controlled region near the capital.
The Russian Defence Ministry said in a statement on Monday that its military police had set up two checkpoints and four observation posts in the area.
Military police had also been deployed to try to enforce a different de-escalation zone in southwest Syria on Friday and Saturday, it said in the same statement, saying two checkpoints and 10 observation posts had been set up there.
"Thus, thanks to measures taken by the Russian Federation, we have managed to stop military action in two of Syria's most important areas," the defence ministry said.
Talks on creating a new de-escalation zone in the province of Idlib were continuing, it said.