I think you've forgotten why there is a civil war raging in Syria in the first place. The U.S. didn't start it, they just took advantage of it (as did Russia, Turkey, and Iran). Syrian civilians started it as a backlash against al-Assad's draconian rule where people were arrested and disappeared with no legal recourse. 

While I agree that the U.S. has no place in meddling with the internal affairs of a sovereign nation, don't think for a second that if the civil war stops that will be an end to the bloodshed.