The unfortunate truth is that this era is so pregnant with false flag operations as to make it impossible to discern the genuine element (ISIS attack/sabotage-operation) from its CIA-MOSSAD-MI5 counterpart.
The Neo-cons who are M.A.D.ly intent upon spreading wars find Russia's deft use of diplomacy problematic. What better way to provoke Russia into retaliation against ISIS (and to an extent, Assad's governance of Syria) than to shoot down one of its aircraft.
As is the case when a famous peace proponent "mysteriously" dies in a plane or car crash, no PROOF of foul play is held up as the argument that there was no foul play. However, the Deep State's assassins know a thing or two about how not to leave any trace of evidence behind.
Besides, when the wrecking crews are immediately called in to remove evidence and a full-court press is ready to supply a Official Narrative that spreads like wildfire across all media circuits to stand in for Truth, it's next-to-impossible to establish TRUE causation and the entities behind the latest calamitous act.
Enter the rumor mill and its legion of expert pundits, advisers, and public consensus shapers.