Western countries, including the United States, blamed Assad’s armed forces for a chemical attack which choked scores of people to death in the town of Khan Sheikhoun in a rebel-held area of northern Syria on Tuesday.

Washington said it believed the deaths were caused by sarin nerve gas dropped by Syrian aircraft. But Moscow said that the poison gas belonged to rebels and had leaked from an insurgent weapons depot hit by Syrian bombs.

The United States, Britain and France have proposed a draft U.N. Security Council resolution that would pin the blame on Damascus. Kremlin spokesman Dmitry Peskov said Russia would argue its case blaming the rebels at the United Nations.

“Russia and its armed forces will continue their operations to support the anti-terrorist operations of Syria’s armed forces to free the country,” Peskov told reporters.