How can he do that, without Russian permission (as when Israel bombs Hezbollah commanders in Syria)?
We dont need Russian permission.
Do you want a nuclear confrontation?
No but we're not a Russian vassal state either.
Just a simple question, did Syrian government allow US troops and airforces come to Syrian soil?
Assad has no legitimacy as the Syrian government. The world has a responsibility to stop the murder of innocent civilians. I don't think ground troops should be sent to Syria, but I think a Libya-style intervention would be in order. At the very least, safe zones and a no-fly zone should be formed to protect civilians from Assad's brutality.