"So the repeated diplomatic warnings, the summoning of the Russian Ambassador, the warnings printed in the international press and the shooting down of the other aircraft wasn't enough?
Are they stupid, arrogant or both"
Neither. More like cunning and calculated. Justification for huge escalation of the Bear's footprint, with consequences for much more than Syrian airspace. NATO will need a very careful, but powerful stance, or this could get uglier very soon. With this move, Russia has threatened free world allies in the region.