Of the nations listed, which one will the U.S. normalize diplomatic and trade relations first?
Cuba, but probably not before the Castro brothers die. North Korea is a very distant 3rd.
I feel the need to explain my vote for Cuba.
Anti-Muslim feelings are very high in the US right now and Iran is an Islamic republic, so normalization of relation with Iran would be unpopular from this side. From Iran’s side: even though a moderate was elected president the real power still rests with the Supreme Leader and the Guardian Council, who are hardline Islamic clerics, mostly old. I don’t think that they’d want normalization with the US, even it’s just so they have a boogey man to distract people with.
North Korea is so messed up I don’t even see how normal relations could happen. The whole cult-dressed-up-as-a-country would have to come crashing down, and then we’d be dealing with chaos followed by (at best) a peaceful, unified Korea or (at worst) atom bombs turning the whole place into an irradiated wasteland.
That leaves us with Cuba. The Super Castro Bros (patent pending) won’t live that much longer, nor will the Cuban-Americans who remember what things were like before the revolution. When they’re all in the ground normalization can begin.