Yeah, I don't want to start this conversation in every topic this question pops up, but I am also tired of hearing either straight-up denial or better yet "it's complicated" excuses. It is what it is, a blowback. I'm not saying it is myopic/close-minded foreign policy (it did speed up the collapse of the Soviet Union) or a mistake, like the Iraq War, but it was also the direct result of their actions.

The Afghan mujahideen were not the same thing as al-Qaeda or even the Taliban.

They didn't have to be. The support for mujahideen created instability where movements of all kinds can flourish. Osama was a "nobody" that sprouted in this environment. He would never have attacked the US if all sorts of radicals haven't gotten a proper operating base in the country. He would never have gotten a base there if mujahideen did not trail blaze a path for them. Hindsight is 20/20, but what makes me hopeful is that now they understand that the option of removing the "stable" government of Assad is not on the table when the IS is the most competent fighting force in the theater and radicals are so ingrained and so powerful among the opposition.