The head of Syria's Al-Nusra Front, an offshoot of Al-Qaeda, urged retaliation for what he said was the indiscriminate killing of Sunni Muslims by Russia.
In an audio message posted on YouTube on October 12, Al-Nusra Front leader Abu Muhammad al-Golani said Russia's military intervention is aimed at saving President Bashar al-Assad's rule from collapse but is doomed to fail.
Golani said insurgents should retaliate by escalating attacks on Assad's minority Alawite sect.
The radical Sunni Al-Nusra Front is one of the most powerful forces fighting Syrian government forces backed by Russia.
Russia says its bombs have struck many Al-Nusra and Islamic State targets. But Golani said the Russian strikes have hit only rebel groups that are actively engaging the Syrian Army, leaving areas run by rival IS mostly untouched.
The Russians only intervened in a "new Christian crusade" after rebel forces threatened Assad's rule, he said, and "clearly know Islamic State does not threaten the regime as the areas it controls do not adjoin the regime's heartland."
Golani promised to "make the Russians forget the horrors of what they faced in Afghanistan."