Really defeating Talibans requires a bit more diplomacy than brute force. It's pretty clear that Pakistan is the key. Cutting of supply to talibans is much more important than trying to eradicate them.

But the real issue is what kind of Afghanistan you leave behind. If you leave the country turned upside down it will most likely just revert to pre-invasion state. So, it's not just "defeat the talibans" thing. Talibans follow certain ideology, and it's that ideology that you have to defeat or at least weaken, not the talibans. It seems that US & co are making similar mistakes as soviets have made...