If you think bad guys are sitting in glaring colourful robes for the US military to come and shoot them, you are way off the mark. Political crisis like this are difficult to contain by external players because you never know the good guys from bad.

Maybe US (and other powerful nations) can stealthily fund the locals and arm them to face the radicals, so that the change comes from within rather than outside. Again the problem lies in identifying the innocent locals from the radicals.

At this stage, I'm not even sure if there is a solution for syrian crisis.