Reuters, Moscow – Russia does not see keeping Bashar al-Assad in power as a matter of principle, the Foreign Ministry in Moscow said in comments that suggested a divergence of opinion with Iran, the Syrian president’s other main international backer.

Fuelling speculation of Russian-Iranian differences over Assad, the head of Iran’s Revolutionary Guard Corps suggested that Tehran may be more committed to him than Russia, saying Moscow “may not care if Assad stays in power as we do.”

While Russia and Iran have been Assad’s foremost foreign supporters during Syria’s four-year-old war, the United States, its Gulf allies and Turkey have insisted the president must step down as part of any eventual peace deal.

Russia intervened militarily at the end of September to support Assad by launching bombing raids on rebel groups trying to overthrow him.

Rebel advance

On the battlefield, a newly-formed U.S.-backed Syrian rebel alliance advanced against ISIS in the northeast province of Hasaka on Tuesday, the Syrian Observatory for Human Rights monitoring group said.

In the west, Russian warplanes carried out airstrikes in Hama province while unidentified jets bombarded the outskirts of the ISIS-held city of Raqqa in the north.