they went to afghanistan as it was a hot spot for terrorists in particular the taliban and al’queda had training camps there for the terrorists who did 9/11
the usa attempted to turn the country into a democracy and move the country beyond being a 3rd world hole but because afghani’s are largely tribal goat herding muslims who have no care for a “state of afghanistan” (or women) the plan failed and the taliban who are largely violent islamic fundamentalists got back in power with little resistance from the locals … who just wanted to go back to hating women and tending to their goats
similar in iraq
generally the people of a country get what they want, i can see in iran there is a growing consensus that they do not want an islamic regime in power
if the us was to kidnap the supreme leader it would be an amazing opportunity for them to ultimately be free
but it depends on what the citizens of that country are willing to fight for
the best modern example is Russia trying to take over Ukraine (again) and the Ukrainians fighting back, they have help from Europe etc but even if they didn’t they wouldn’t have just sat on their hands, they would be fighting today a guérilla war in kyiv like they have in the past