"They hate us for our freedoms"

Or maybe they're just pissed we invaded Iraq for no damned good reason:

WASHINGTON - New investigations by the Saudi Arabian government and an Israeli think tank — both of which painstakingly analyzed the backgrounds and motivations of hundreds of foreigners entering Iraq to fight the United States — have found that the vast majority of them are not former terrorists and became radicalized by the war.

The studies cast serious doubt on President Bush's claim that those responsible for some of the worst violence are terrorists who seized on the opportunity to make Iraq the "central front" in a battle against the United States.