Assume Obama and Kerry hadn't spent the last month hitting each other in the face with cream pies. Assume for a minute that Obama's soaring rhetoric convinced America to pinprick, err, surgically strike Syria. If either Syria had retaliated in some way or Assad had fallen and it looked like the Al Qaeda goons in the rebel armies were going to grab mustard gas stockpiles, then what? There's no way to follow up on this without the fabled Boots on the Ground.
Just where were we going to stage such an invasion? At sea? With what?
How do you inject, say, 100,000 troops into Syria with no land borders on the place? Syria is geographically large and the damage from either a collapse or a significant retaliation wasn't going to be contained by drone strikes. Not only was nothing prepared for these eventualities, it's not immediately obvious that anything could be prepared. For one, we managed to vacate the best place of all to stage such a force - Iraq - and for another, we've got nothing like the kind of fleet required to support such a massive invasion from the sea.
Everyone wants to focus on the gossipy part of the collapse. Putin dunked on Obama, Putin wrote a snarky op-ed, Obama gave a lousy speech, Kerry rotated his feet through his mouth on a daily basis, Chuck Hagel smeared library paste all over his sleeves while working on his construction paper art project and so on. It's irrelevant. There was no practical way to follow up on the strikes and our enemies all knew it.
The speeches and idiocy were just decorations. The real failure occurred when we gave up on bases in Iraq. Without them, all we were ever going to have were speeches and a couple of cruise missiles. That's no deterrent to a guy who's willing to gas thousands and others who are willing and able to support him.
This is what landing 100,000 troops looks like.