Another round of Russia-US talks on ending the bloody conflict made no progress at the weekend as the Syrian president's forces closed in on the last pockets of rebel resistance in Syria's second city, Aleppo.
French Foreign Minister Jean-Marc Ayrault said the talks failed "because there is double-talk and a sort of permanent lie" on the part of Russia.
"On the one hand they say: let's talk, let's talk and get a cease-fire," Ayrault said as he arrived for a regular meeting of European Union foreign ministers in Brussels.
Ayrault said Russia had concentrated so much effort on Aleppo that it had allowed IS jihadis to recapture the ancient city of Palmyra, revealing Moscow's real priorities in a conflict which has cost more than 300,000 lives.
IS overran Palmyra on Sunday, nine months after being expelled by Assad forces backed by massive Russian air attacks.