Can someone please explain to me what is going on in Syria?

Secretary of State John Kerry is channeling Dick Cheney in leading the charge to attack Syria!

The Republicans are arguing against military action!

Maybe I have missed something, but I have not seen an intelligent discussion of any US security interests in attacking Syria.  Can someone explain Russia’s interest (other than poking the US).  I think I can understand why Iran is defending Assad, they need a proxy to distract the US and to pressure Israel.

But, is it in anybody’s interest to have Syria in complete chaos?