Ugh, do duh? What? Am I missing something here?
motive = (a) to kill as many USA highly trained military personnel so they can’t go to the war zone and harry and harass the Islamist fanatics, (b) to make it impossible for folks to be at ease in a fortified USA military base on USA soil so they lives with a high degree of unease and anxiety (i.e. terror), (c) to prove to other Muslims that you can pull off such a stunt with the full support of the FBI, President, Army Chief of Staff and all USA media (except Fox news - which really is not a new organization anyway).