@GreenKnight121
Israel is a strategic nuclear power. With around 200 warheads and Jericho III ICBMs to deliver them with.
Their military has a long history of striking with impunity anywhere they want to. They are exceptionally well trained, motivated and equipped. For instance we got much of our UAV technology from them and they lead in ABM technology.
They are a democracy with a popular and very strong prime minister who can be guaranteed to act as and when necessary. Mossad, their intelligence agency, knows more about what is happening inside Middle Eastern countries than their own leaders do.
Russia is a clapped out and highly corrupt shamocracy which is depopulating and has a critically ageing demographic. Their economy depends totally on gas and oil. They are led by an unpopular idiot dictator who postures like Mussolini and who is afraid of girls (Pussy Riot). Their military is also highly corrupt and based on a culture of bullying. They have trouble getting their rust bucket ships to sea or their geriatric aircraft in the air. A typical military breakfast includes copious vodka.
Syria is in the Eastern Mediterranean, an area where Israel has had overwhelming military capability for decades and has demonstrated this comprehensively and repeatedly.
Russia's presence in the Eastern Mediterranean is several levels down from that of the boy scouts. If they do anything that strategically raises the threat against Israel then Israel would have no compunction in acting, quickly and with full force. If Russian "technicians" are casualties then Israel will not give a damn. And Putin, for all his posturing stupidity, knows this.