Russia has confirmed that it IL-20 Surveillance Plane with 14-15 people aboard was shot down by Russian-made air defences operated by the Syrian military.
The Russians are understandably upset and are calling Israel irresponsible for attacking Syrian & Iranian bases near the Russian Latika base while Russian planes were coming in to land. http://www.israelnationalnews.com/News/News.aspx/252154
However the Russians have no one but themselves and their incompetent Syrian allies to blame for this tragedy.
It has been clear for years now that Syrian "air defences" are much more dangerous to their friends than their Israeli enemies.
Israel has launched 1000s of sorties over 5 years and Syria has managed to hit only one Israeli plane in all that time, and this was only because the Israeli pilot (who survived unharmed) forgot to turn on some system that makes Israeli planes invulnerable.
If Russia wants to keep its planes safe it should tell the Syrians to stop firing at Israeli planes - they are wasting their time and ammunition and endangering their people and allies.
Also, Russia should have stopped Iran & Syrian building bases really close to Russian bases, trying to hide under mother Russia's skirt. Israel has massive military superiority over everyone else in the area (including the Russians) and has made it clear that it will destroy all Iranian attempts to build bases in Syria.
Iran thinks Russia will protect it, but it can't and won't.
Israel is too strong, too important to Russia and probably the only advanced nation that has never attacked Russia. (Russians have long memories.)
In contrast Russia and Iran are historic foes and Iran is dying. Russia is happy for it to provide cannon fodder but has no long term interest.