Based on this article here. This article, incredibly enough, was written by an American leftwinger, but the US Left is pathetic and disastrous on the subject of Russia.
Assad or the Syrian régime may once have been an asset to Russia, but it is now a liability…Yes, the West could do more, but only Russia could put an end to the fighting without expense or risk. Russia could from one day to the next stop direct support of the Syrian régime and pressure Iran to do the same.
Russia could drop its Security Council support for the régime, unleashing vastly increased Western pressure on Assad. All this would cost Russia not one penny, not one life. Given this is more like common knowledge than a secret, why doesn’t it attract more attention?
I do not believe that Russia will ever give up Assad, especially not now. In a way, they see this as an existential battle for Russia. Russia (and China) think that all of these regime changes, color revolutions and ensuing chaotic failed states run by Nazis and Al Qaeda types are a US plan to sow chaos and discord in the region. The US is the “agent of chaos.” Russia (and China) figure that they are next on the hit list for America’s agents of chaos. They think we are going to unleash are pet Nazis/jihadis against Russia and China and they might be right.
Iran on its own would know Assad was a lost cause, and he would fall.
Iran will never give up Assad. Iran sees this as a fight for survival. These jihadis are ferociously anti-Iran and their agenda can be boiled down to “kill the Shia.” Iran is a Shia Muslim state. Given their anti-Iranian and anti-Shia ferocity of these jihadis, Iran sees them as an existential threat. Of course, they also wish to protect their Syrian ally, which is also rational behavior.