Everybody's upset because Vladimir Putin is making a play to establish a Russian influence hegemony in the middle east, to replace the American influence hegemony that has worked so splendidly for us there.
He wants to prop up Syria's ruthless dictator Bashar Assad the way the Americans propped up Iran's ruthless dictator Shah 40 years ago, Egypt's ruthless dictator Hasni Mubarak, and even Iraq's ruthless dictator Saddam Hussein, at least until he became public enemy #1 by invading Kuwait.
Do we Americans think that we alone have dibs on middle east meddling? Putin wants to help Assad stay in power by destroying ISIS for him. At this point, given that Obama has done nothing to deter ISIS in the slightest, why not approve of Putin installing a puppet regime in Syria if it means ridding the world of ISIS? We can worry about the Russian presence later. If Assad falls, ISIS takes over the entire country of Syria and they hold most of Iraq already.
Do we want that? Which is worse, ISIS running rampant all over the middle east or Assad treating his people barbarically, while keeping his boot on the necks of the ISIS rabble? Additionally, if Russia exerts its influence in the middle east, maybe ISIS, Al Qaeda, and the Taliban will direct their collective ire toward Moscow rather than the US for a while.
I'll go with Assad for now and I'll bet all the Syrian and Iraqi Christians with headless family members would agree.