i need to know this about terrorists in wake of the beheading

Why go after Americans? I mean... There are thousands upon thousands of Middle-Eastern people and governments who are in favor of and support American initiatives. If I were a terrorist, wouldn't I see them as worse for facilitating Americans?!?!? See Comments.

Update: This is pretty complex... see the interview with the CIA officer which is a more recent story. In short, they are, and they have, and... well... Just keep digging out there, and you can find the truth to be more murkier than TV would have you think.