One thing is for certain. There is no logical reason for Assad to do a chemical attacked that could be carried out just as effectively with conventional weapons. The use of chemical weapons only has downside for Assad and no real upside. Whether or not it's a false flag, I don't know. I think the simplest most logical answer is that our so called "Moderate Rebels" carried out the attack as a way of getting the US more involved. They have the most to lose if we leave and the most to gain if we stay.