Actually, during the 70's when a certain president was hell bent on Communist Russia, we provided weapons to a certain group of people in the Middle East. At that time they were not Al-Qaeda, but those same people today still have those weapons we provided to get rid of Russian occupation in the Middle East.
I suggest taking a Terrorism and Homeland Security course in college even if Criminal Justice isn't your major. Terrorism has been around long before the Holy Crusades. People look at the Roman and Persian empires to justify terrorism or reasons to go to war. However, people look at those as dynasties. I look at those times as tyrants who wanted to wipe out an entire race (genocide) and to this day terrorism is still rampant. Our history NO MATTER WHAT justifies it rightfully or wrongly.