I hate to be completely cynical, but if I were a leader of a rebel group in Syria and the war hadn't been going my way for the last several months, I might consider getting hold of a chemical weapon and unleashing it on innocent civilians. What better way to get the U.S. and our Western "allies" involved? I would know that suspicion would fall first and hardest on the Assad regime, and that there would be an outcry in Congress for Obama and the U.S. to do something--shoot at somebody and figure out later whether it was the right target.
I'm hearing that the administration has satisfied itself that "the regime" is the responsible party in this case. And I read earlier today that a key congressman said Obama should go in shooting EVEN without any Congressional action to authorize such action.
I just hope that before any bomb gets dropped or missile fired, someone--maybe another Edward Snowden--will vouchsafe us peons a peek at the evidence that justifies it.