[Reaganite Republican]

Another possibility:

“...SA-8 GECKO was used to down a cargo plane around Damascus by Syrian rebels last year which is highly mobile and has the range of 40,000 feet, well within distance of the reported height (36,000 ft).

http://therightscoop.com/heres-how-isis-could-have-shot-down-that-russian-airliner/

Something like this could have come from the US side, via the CIA Benghazi weapons bazaar... who knows what they were up to. And the Americans let a lot of Russian stuff go from Ghaddafi’s armory to the Islamists too... that’s on our, France, and UK’s hands.

[Hulka]

And no, SA-8 leaves/uses radar so there would have been a ELINT signature (Acq and TTR) that would be detected by almost everyone in the region, especially the Israeli's. Like turning a flashlight on in a dark room, it is noticeable.