This indeed sounds serious. The rhetoric from both sides reminds the cuban crisis in 1962.
Hot heads should be calmed down.
IMHO all the high-ranked generals (again, on both sides) should be locked somewhere in a movie hall for a couple of hours and re-watch stuff like "Fail Safe" or "Dr. Strangelove".
Remains of ISIS and Al-Nusra (supported by US) or Assad's regime (supported by Russia) do not deserve such attention to put the whole mankind at threat.