I think its both. Blow back is an understandable reason for some hatred towards the west from their point of view, we can say we were looking towards our best interests while they (in some cases rightly so) can say we are an evil country invading their land causing havoc. Ron Paul mentioned the 1953 coup in Iran(which was Britain's quest imo) and the Gulf War for most of the blow back, of course there are more cases like our alliance with Israel and our occupation of Saudi Arabia but there must be more reasons for their hatred.

Am I to believe that all of the terrorists in-training are educated about American foreign policy beginning over 60 years ago so they can logically come to their own conclusions as to why they have reason to strap bombs to their backs and blow themselves up? In my opinion there may be several intelligent men who organize and control these terrorist groups but the rest are just breed to hate America since they were born.