I cannot see any huge problem with limited strikes on government command and control centres and on a few military targets, like airfields and missile sites. Apart from acting as a warning against the use of (further) chemical attacks, it would even the fight a little and let Russia know it cannot have its own way. It would be nice to have a UN resolution, but Russia and China will never let that happen.
Give Assad a bloody nose and then stand back for a while.
So you think we should 'even' the conflict up a bit then, what happens if more Sarin is deployed and we don't know who used it some days ago, both sides have the rocket based systems to deploy the gas.
So who do you hit, we have no confirmation of a) where all the regimes CW stockpiles are, b) has security on any been compromised c) have the FSA captured any, d) is it 'bathtub Sarin' as used in the Tokyo attack. What about the consequences after a strike, do we allow mass slaughter by the rebel forces of those seen as either unbelievers or not believing enough, which has happened in the past look at Iraq and it is happening now in Syria and has happened in Egypt before the military got involved.
What would the Russians and Chinese do, Russia could cut off gas supplies to the west and China call in all the US debt it owns, the rule of unintended consequences. What happens if the rebels won then they had Sarin and the means to attack, would they go after Israel at a later date, and the consequences of that are even worse, with the potential of nuclear weapon release as would have happened in GW1 with the Samson option. Remember, James Baker via Tarriq Assiz warned the Iraqi's off quietly through the UN about the potential consequences of a CW attack on Israel.
Time to stand on the sidelines and watch, help Jordan and Turkey with the refugee situation by all means but get involved inside NO NO NO.