But you're talking very generally: we are independent militarily: if the US attack us, we can attempt a defense. If Afghanistan could free itself eventually, I'm sure we can find a way as well. My country has nukes (and owns the territory launching Ariane rockets) and NATO can't tell us what to do with them.

NATO is not a US-controlled army defending Europe. It's a collaborative alliance to scare a bit anyone trying to invade us, but it's not gonna do us any good if the US decide to become crazy or if one of their critical allies attack us and they don't want to risk it.