Did the Rooskies turn off their system....or did we? Or someone else a little south of Syria?
Probably a deal with the Russians.
It would have been more interesting if the Russians had tried to shoot down the missiles.
There would then be a better idea of the quality of Russian systems.
But thats a risk to the Russians, it benefits them to hide both their qualities and their deficiencies. If they are bluffing, they can continue to do so. If they aren’t bluffing it hampers their rivals in the R&D leapfrog game.