I am the last person to ever claim that Vladimir Putin is anything but a vicious dictator, who deserves to be put down any way possible, but that does not neutralize the fact that Russia has an urgent interest in seeing to it that no group of Islamic fanatics, like ISIS, takes control of Syria.
Here's a map of the northern Middle East and southern Russia. Please note that the distance between Syria and Russia is, at the narrowest point, only about 250 miles. That is a distance that could be covered in less than half an hour by a fighter jet, or less than four hours on a straight freeway drive, if a freeway existed there.
I ask anyone to consider what the United States would do if a genocidal Islamic state arose 250 miles into Mexico; which is to say, around Mazatlan. Do you think we would not be bombing the whole area into oblivion, regardless of the civilian "collateral damage?" After all, we killed a million civilians in Iraq just a few years ago, for nothing. And please consider this question in light of the fact that the United States has, for over a century, maintained vicious dictators throughout central and South America; dictators that have been every bit as brutal as any Islamic ruler, and that our country has done this in the face of far less threat than Russia faces from Islamic extremism. Many of these countries posed no danger to anyone except American corporations, before we destroyed their governments. This reached a height of abomination in the fifties, when the Eisenhower administration essentially turned foreign policy over to two brothers who were on the board of the United Fruit Company, and who used their positions to see to it that no Central American country ever acted in the interest of its own people, and during the Reagan administration, when the Republican President illegally financed an army of drug gangs to force a legitimately elected government from power; these monstrous interventions continue to produce disastrous effects for our own country today.
No matter how vicious Putin may be, the reality remains that Russia cannot tolerate a fanatical, genocidal government almost on their border. We would do well to keep that in mind as we see how Trump's current temper tantrum plays itself out.