More and more I believe, the US military is a Saudi tool these days - to kick Assad and Iran. "Pay the oil with military power and keep your worthless greenbacks".
And a cornered Obama runs a show right now, telling his will to act, but in need for the Congress legitimation to attack. "Sorry may oily Prince, I tried everything to follow your wishes, but I can't break my own laws, you know. But I can deliver more weapons, training and intelligence to withdraw Assad and his friends."
I see only one justified solution for Syria: according to the R2P (right to protect) rules, an international force with superior tech should enter Syria and install safe areas along the borders for the Syrian civilians. Expand these areas from the borders and destroy any resistance. No strategic important terrains, but a passive no fly zone over these areas.
No support for any fighting party in Syria, but the safe place for the pepole who choose to stay out of the conflict. That's the R2P spirit. Let Assad and the aggressors fight their dispute, but save the peaceful people. When done, ask the protected people, if they want to fight the remaining party (and let them do!) or if they want to accept the winner.
This should consequently be done in all the conflicts worldwide, to bring them to an end.
It would be possible, if there were no further interests of members of the international community concerning Syria - and no interests of war profiteers around the world.