Ok, let's forget the chemical attack for a second.
The point of the US, UK, France attack was not to kill but to take away Assad's assets so he can't use them against his people.
I really enjoyed the books. They can be dark at times though. There is a third book out "The Magician's Land" but I have not read that one yet. For some reason I thought the TV series was linked to the movies of a similar name, I am definitely doing to seek it out now.