It's true that experts differ as to whether the advanced air defense systems already in Syria can bring down stealth aircraft, but it would be a mistake to dismiss this warning out of hand. Besides, Konashenkov added, in a telling ex-ante-extenuating-circumstance vein, that Russian air defense "will not have time to identify the origin" of the aircraft.

In other words, U.S. aircraft, which have been operating in Syrian skies without Syrian government approval, could be vulnerable to attack with the Russian government preemptively warning that such an incident won't be Moscow's fault.

As for the prospects of reviving the Syrian negotiation track, its demise was never clearer than in the remarks on Sunday by Foreign Minister Sergey Lavrov in a lengthy interview with Russian Channel One. He ended it with a pointed comment: "Diplomacy has several allies in this [Syria] endeavor – Russia's Aerospace Forces, Army, and Navy."