... what he just said!
I think the good Major probably started off as a 'good American' (about as good as an American as an Arab-Muslim-American can get! ) and planned to serve his country (as opposed to his religion) as best he could in the U.S. Military.
But things got turned around somewhere along the way.
There's a lot of propaganda out there floating around by terrorist organizations (and others) ... and being globally connected to it doesn't help matters a whole lot, either. He apparently got caught up ... and was definitely in the wrong situation at the wrong place and in the wrong time!
Maybe he wasn't a "plant" ... maybe the terrorists just found him already growing in the middle of a garden and decided to water him ... until he bloomed into a mass murderer.