[UPDATE: here. Apparently Israel is taking this worry seriously]
According to DEBKA, Putin has threatened Netanyahu with introducing the advanced S-300 anti-aircraft missiles into the Syrian theater in case of further Israeli airstrikes. (DEBKA chastises Netanyahu for making a stop in Shanghai during his China trip, which allowed Putin to deliver the message in person).
As DEBKA points out, it appears from this event that Israel has underestimated the consequences of the weekend strike on Damascus. Otherwise Netanyahu would surely have avoided running into Putin. But is it really thinkable that Russia would introduce advanced SAM batteries to Syria at the time the West considers a no-fly zone? That would certainly be the most brazen sign yet of Russia re-assuming its Cold War posture, as well as proving an ironclad commitment to Assad’s survival.