9/11 gave rise to some debate over precisely where Islamic antagonism against the West began. The Bush Administration babbled out some stupid shit about freedom, while "BECAUSE ISLAM" became the refrain of the administration's supporters. Democratic politicians took an ideological vacation for eight years, refusing to speculate one way or the other, while those of us in the trenches in the anti-war movement were pretty convinced American foreign policy was to blame.
Being the fairly intelligent person I am, I automatically discounted both the Republicans and their useful idiots, but in retrospect the people I was protesting alongside weren't exactly correct, either.
Foreign policy is Johnny-come-lately to the Islamists' list of grievances. It certainly exacerbated the problem, but the problem was there long before the United States started dropping bombs on the Middle East, North Africa, and Central Asia.
Rather, it seems to have gotten its start in the 1950s and 1960s, when American workers started showing up in Saudi Arabia to pull oil out of the ground there. The clerics weren't too pleased with what the infidels brought with them: alcohol, movies, music, a comparatively libertine approach to human sexuality. They didn't like this stuff, fundamentally at odds with traditional Islamic morality, mere miles away from Mecca and Medina. They were even less pleased the jahili Americans enjoyed the full support of the Saud monarchy. That the Saud monarchy, which the clerics hate with an unrivaled passion, is even more infuriating.
Part of the reason we've been targeted by Sunni extremists is because we are seen as empowering and protecting an unpopular regime. They think if they can scare us into breaking our alliance with the Sauds, they'll be able to overthrow the family and reinstate the Caliphate there.
In any event, our presence in the Middle East is toxic. Any moderate or liberal faction lucky enough to receive our support would immediately become suspect as pawns of the Great Satan. We'd be undermining their cause, and presenting ourselves as targets. It simply isn't worth it. If system change is going to come to these countries, it has to come from within. Without our help.