“[…] What happened on September 11 has virtually nothing to do with economic globalization, in my opinion. The reasons lie elsewhere. Nothing can justify crimes such as those of September 11, but we can think of the United States as an ‘innocent victim’ only if we adopt the convenient path of ignoring the record of its actions and those of its allies, which are, after all, hardly secret.” (Noam Chomsky)
This quote is from a little booklet by Chomsky about 9/11. Not everybody likes Chomsky, but if you are interested in a non-mainstream perspective that tries to go beneath the surface, check this book out.