Hindsight??? LOL... we've been warning you for years.
The US should not be playing the world's policeman, sticking it's nose (UnConstitutionally, I might add) in other peoples affairs.
This does not excuse the attacks today - but if you want avoid repeats, for real... stop meddling in the affairs of other nations.
What nations are you referring to?
If the answer to that question is "Afghanistan," here's a follow-up: Who was more than happy to receive weapons and training from American entities when the Soviet Union was invading their country?
You think this is a big f***ing joke DAnconia55! Thousands are dead and you laugh over what you precieve as a lesson not learned. I know somebody who lost his sister in the WTC. My brother scrambled for his life to get out of the WTC and you laugh and think it is a big joke.