from Russia Insider:
Russia has no good options here. Russian military retaliation brings the absurdly pro-Israeli American public opinion and Washington establishment into play. Doing nothing signals weakness and invites more provocations
It’s technically possible the Russian Il-20 surveillance plane was downed only as a result of stupidity and incompetence on the Israeli and Syrian side, and without a devious Israeli plan to set it up. Militaries almost always are among the stupidest and incompetent of all government bureaucracies so it’s in the realm of possibility.