There is a simple solution to the dilemma... run a covert operation to assassinate a key Assad government official such as the defense minister. It sends the 'red line crossed' message to Assad, there would be no civilian casualties unlike a cruise missile bombing mission, and limited aggravation of Syrian allies. Done, done, and done. And no congress approval required either. Am I missing something here?
I would go for this. However, the real aim is to replicate Libya: i.e. regime change in Syria by destroying Assad, his loyalists and his armed forces. Can't do that with a hit squad. Can't say it because it would violate intl law.
The whole chemical weapon argument is a diversion and "utterly nonsense".