The Russian aircraft wings are not located near the tail as they are in the ISIS video. That video is either faked or of another incident.
I am of the opinion it was probably one of the many thousands of MANPADS that went missing out of Libya after Obama got Ghadaffi overthrown in his jump-start of the Global Caliphate (aka: Arab Spring). Russia has been doing what we have not in regards to laying waste to ISIS.
I think saying a bomb was planted is a lot easier for the regime to deflect responsibility than to suggest it was a SAM, because the panic-factor among the public is going to be a lot higher if it becomes known ISIS has capabilities to take out airliners from the ground.
Bottom line, regardless if a bomb or a missile, this was Jihad terrorism.
Something else Obama and his Jihadist-loving regime refuses to state.