We are not there to “conquer” Afghanistan. We are training their military, not fighting it. And besides, Afghanistan is full of individual villages who give zero fucks about who is in charge of their weak central government. As far as they’re concerned, they answer to the village elders, their imam and their god. There is no nationalist identity. The Afghan borders are a meaningless concept to the majority of its citizens. The country cannot be “conquered” in the since that one government takes control of it with military force, because even it’s own government has never fully controlled it.
But that’s all besides the point. Struggling with an insurgency does not negate the fact that the United States is a military superpower–the absolute strongest in the world by orders of magnitude. And that has little to do with nukes. Look at the number of trained personnel, the equipment, the global projection, the logistics capabilities, our carrier groups, our airborne brigades, etc.
I don’t even see how you can debate this. Regardless of whether American is the greatest country on Earth, the simple fact is that (for better or worse) it currently has the most powerful military. If we wanted to actually destroy Afghanistan, it would not be difficult even if restricted to conventional means. We have enough bombers and conventional munitions, and enough maneuver brigades to wipe out the entire country, and go house to house and kill every last person. That’s actually a lot easier than trying to fight an insurgency while avoiding civilian casualties. Total destruction of the country was never the mission. We literally started that war on horse back, and there was never a massive bombing campaign set out to level Kabul.