It does. The Russians are a shell of their Cold War selves, but they're still a shell with nukes. They probably wouldn't appreciate their dudes getting killed. I don't think they'd go full retard, but they might cut off energy supplies to Western Europe right as winter hits. They'll let the Germans suffer for a few weeks, then offer to turn the spigots back on if we leave Assad alone. They'll point out he's not nearly as bad as ISIS after all and this would reduce that nasty refugee problem that's been in the news so much. They're gambling that with us having an election upcoming, the current administration will opt to declare victory and go home so the issue disappears before the primaries. How Obama reacts, I have no idea.