The Taliban were a tiny splinter group before the US financed and trained them. They have always been fanatics. Funny how they were not called terrorists while the US thought they could use them for their own ends.
Also I think they changed their allegiances, so they became terrorist towards US people?
Funny you ask... It was called the cold war, you might want to look it up. US was a pretty big player there.
Before cold war, there was WWII, and communist revolutions.
I don't want to defend any particular war, I just think it may all be a bit more complicated than a simple "we shouldn't have started any wars".