Iran is also an ally of Syrian and Russian and involved in the war. So war with Iran, too.
And probably with some of the former Republics that would ally with Russia. Chechnya has thousands of special forces fighting in Syria.
China if taking sides would probably side with Russia, who is taking care of Chinese Uighur muslims fighting with IS and al Qaeda in Syria
Russia actually has a well supplied and killer military. We have a giant social integration experiment with faggots, women and sexual deviates mixed in . We wouldn’t last for 3 days. What did Syria do to US???
A less impossible mission had aircraft carrier Iraq not been scuttled.