RE:

curious, how you view putins argument that the u s helping the syrina rebels is illegal, and russia that will back a legal govt has a stronger moral position

Legally, he has a strong case. Morally, support for the legal government is criminal. As for support for the rebels, that's a complex story. US allies Saudi Arabia and other Gulf states have been supporting the worst of them, including IS, and probably still are despite denials. US NATO ally Turkey is supporting the al-Qaeda-affiliated al-Nusra front, ideologically the same as IS though there's a turf battle. The US spent hundreds of millions of dollars for several years of training of "moderate" rebels. The Pentagon sent all 50 of them into Syria and they were instantly wiped out (or defected) to the al-Nusra front, apparently with collusion of Turkish intelligence. The Pentagon now says it has about 4 or 5 trained "moderates."

If it wasn't so horrible, it would be comical.