President Trump harshly criticized North Korean leader Kim Jong Un at the United Nations on Sept. 19, calling him "Rocket Man" and threatening to "totally destroy North Korea" if need be. (The Washington Post)

Imagine you’re Kim Jong Un. You just watched on television as President Trump went to the United Nations and gave a speech in which he demanded that you give up the weapons program that you have worked to make a source of intense national pride. He also threatened to kill you and all 25 million of your citizens, and even called you “Rocket Man,” and although you actually kind of like that nickname — you love your rockets, after all — you know that he’s trying to belittle you.

Are you going to say, “I think I can work with this man; perhaps we can arrive at a deal that will be good for my country”?

Of course not. That isn’t to say that Trump should be showering Kim with praise, but everything he says seems designed to ratchet up hostility with North Korea and make a military confrontation more likely, even when he’s speaking at an institution whose purpose is to promote world peace.

Here’s part of what Trump said at the United Nations Tuesday:

“The United States has great strength and patience, but if it is forced to defend itself or its allies, we will have no choice but to totally destroy North Korea. Rocket Man is on a suicide mission for himself.”

You might argue that the threat to utterly destroy your adversary is at the heart of nuclear deterrence, which is true. But saying it out loud creates a different kind of atmosphere. And it’s critical to keep in mind that we aren’t just trying to deter North Korea from attacking us or an ally such as Japan; our goal is to get them to agree to give up their weapons. It’s not just a matter of them not using them. We’re asking for something much harder for them to give.

There’s another factor weighing on North Korea’s calculation that is vitally important: the Iran nuclear deal. Whatever you think of the Iranian government’s other behavior, according to every informed source — and Trump’s own national security aides — they’re complying with the terms of the agreement they made with the United States, Russia, China, Great Britain, France, Germany and the European Union. They are not at the moment pursuing nuclear weapons. But here’s what Trump said about them at the U.N.:

“The Iran deal was one of the worst and most one-sided transactions the United States has ever entered into. Frankly, that deal was an embarrassment to the United States, and I don’t think you’ve heard the last of it, believe me.”

Which is pretty much what he says whenever he talks about it. So again, put yourself in Kim’s position. The United States is demanding that you give up your nuclear weapons, presumably as part of some kind of negotiated settlement that would include something you’d receive in exchange. But at the same time, the American president is threatening to withdraw from a carefully negotiated agreement Iran made with the world’s leading economic and military powers, in which it set aside its nuclear weapons ambitions in exchange for a package of economic incentives. If the United States is going to renege on that deal, why wouldn’t it renege on a similar deal it made with you? Then you could find yourself without your weapons, and without the economic help you had been promised.

Not only that, we know that the North Koreans talk a lot about the experience of Moammar Gaddafi, who agreed to give up many of his weapons programs, but ended up being deposed and executed in a revolution that was aided by the United States. Dan Coats, Trump’s director of National Intelligence, made this clear at a public appearance in July when he said this:

“There is some rationale backing [Kim Jong Un’s] actions which are survival, survival for his regime, survival for his country, and he has watched I think what has happened around the world relative to nations that possess nuclear capabilities and the leverage they have and seen that having the nuclear card in your pocket results in a lot of deterrence capability. The lessons that we learned out of Libya giving up its nukes and Ukraine giving up its nukes is unfortunately if you had nukes, never give them up. If you don’t have them, get them.”

Does Trump actually think that if he issues a few more bellicose threats then North Korea will agree to give up its nuclear weapons? It would not be unreasonable for Kim to believe that his nuclear weapons are the only thing keeping the United States from launching a war against him.

There may be no way around the reality that Coats laid out. There may be no way to convince Kim that there’s a better future that could await him and his country if he gives up his weapons. But he certainly won’t believe it if Trump is so loudly trashing the Iran nuclear deal and threatening to pull out of it at the earliest opportunity. Why would Kim ever believe a thing he says?