Russia is striking back after a "stab in the back by an accomplice to terrorists" by changing the "game" in Syria. Moscow's retaliation is not just about severing economic and diplomatic ties. It is pursuing a policy that could tie Turkey's hands in Syria. Ankara never received international backing for a safe zone across its border, but Russia has now ruled that out. The deployment of S-400 anti-air missiles means Russia has effectively imposed a no-fly zone over Syria. And now, Moscow seems to be moving closer to a group that has been the US-led coalition's main ground force in...