What are we not being told?

What is interesting are the reports on what intelligence the west has on the chemical weapons attacks. One of the papers, OK it is the Daily Mail, quotes a US "official" saying that it is no slam dunk that Assad authorised the attacks. There are quotes from the JIC report given to David Cameron which asserts that there are 14 previous attacks by Assad and that in all probability this latest one was from him as well. It makes me wonder if we knew about 14 previous attacks why we did nothing then and suddenly feel the need to do something. I do not normally believe in conspiracy theories, governments are generally too incompetent to arrange anything remotely sophisticated, but I am beginning to wonder about what we are not being told.