MOSCOW (AP) — Syria’s most powerful ally, Russia, said for the first time Thursday that President Bashar Assad is losing control of his country and the rebels might win the civil war, dramatically shifting the diplomatic landscape at a time of enormous momentum for the opposition.

While Deputy Foreign Minister Mikhail Bogdanov gave no immediate signal that Russia would change its stance and agree to impose international sanctions on Assad’s regime, his remarks will likely be seen as a betrayal in Damascus and could persuade many Syrians to shift their loyalties and abandon support for the government.