Does anyone think that situation resolved well? If we were able to go back in time, would we choose diplomacy again, knowing it would fail?
Maybe that's why NK has nukes. They US declared war on them and then threatened them with nuclear weapons to prevent North Korea from winning the war.
I don't think we've seen the resolution of that situation. We will one day, and I think the chances of it being a good outcome are pretty slim. I'm very much against Iran having nuclear weapons. I just hope we don't get dragged into a long war which will explode our national debt and potentially lead to a sovereign debt crisis.
There was never really any other option than "ask nicely to not do that", and maybe try some covert sabotage here and there. Everyone knew that and everyone knew that everyone knew.
In Iran the situation is different, because everyone knows that they don't have any such deterrent and they will lose in any real shooting war, with fairly little options to meaningfully fight back. There is a real inventive to actual pursue diplomacy for Iran which didn't exist in North-Korea.
Also the North-Korean regime and population is of quite a different nature than Iran. By and large, the North-Korean regime just wants to be left alone and is quite isolationist. This also doesn't really apply to Iran.