If you want to know where TERRORISM stemming from "Islamic Radicalism" ACTUALLY comes from; highly suggest reading this article. The sect of Islam known as "wahhabis" (also the religion of the current Monarchy of Saudi Arabia), is more or less interchangeable with Islamic Radicalism (since almost all terror groups stem from this philosophy).
Saudi Arabia has been known to CONTINUOUSLY fund terrorism literally EVERYWHERE in the world yet we do absolutely nothing to them. They're also LIVING, BREATHING PROOF; that you can pretty much do whatever the hell you want if you have $$$$.
For as much as the wahhabis and Saudi Arabian Monarchy and Elite of Saudi Arabia despise all other sects of Islam (or as I like to say, ACTUAL Muslims); they despise Western Culture much, MUCH more (so much for our greatest "ally" in the Middle East eh?) and would love nothing more than to wipe us all off the face of the earth (after they're done selling us oil of course).
Hopefully, someone will actually do something about this someday. Until then, that's where nutjobs like Osama come from;The More You Know :).
(Note: I don't know exactly how much of this is true, I know at least MOST of it is true because I researched a fair amount of it and already knew a fair amount; however I still need to cross-check and cross-reference a few of the details and sources).