"After the provocation in Idlib, this was to be expected, although we hoped that common sense would prevail," head of State Duma's Committee on International Affairs Leonid Slutsky said.
"Obviously, the [US] moves not against the terrorists, but against [Syrian President Bashar] Assad, unfortunately, continue. We, on our part, will continue the course aimed at reconciliation and the creation of zones of de-escalation," Slutsky stressed.
On May 18, the coalition conducted its first airstrike against the pro-government forces, which the United States believes are backed by Iran, as it was moving inside a well-established de-confliction zone in southern Syria.
The United States and Russia signed the bilateral memorandum of understanding in October 2015 to ensure their flight safety during combat missions over Syria.