Jeffrey Lewis is a scholar at the Middlebury Institute of International Studies at Monterey.

It’s hard to imagine that this will end well. (Ahn Young-joon/AP)

My greatest fear is a reality: A lunatic has gained control of nuclear-armed missiles that could reach halfway around the globe. And, to make matters worse, Kim Jong Un has them, too.

I jest, of course: It is unfair to compare the president of the United States to Kim, a man who has allegedly executed people with antiaircraft machine guns and worse. President Trump has not shot someone on Fifth Avenue, at least not yet, but as someone who studies nuclear weapons and their uses, this doesn’t comfort me. With Trump in the White House and Kim at the helm in North Korea, nuclear deterrence, the bedrock of U.S. security policy for the past 72 years, seems to be in peril. Staring at Trump and Kim, each armed to the teeth with nuclear weapons, we have to ask ourselves whether we really think that no leader would ever be so reckless as to plunge us into the nuclear abyss and that mutually assured destruction can be safely relied upon indefinitely to preserve the peace.

The very phrase “mutual assured destruction” is a calumny, a term of abuse created by those who wanted the United States to plan to fight and (somehow) win a nuclear war. The Kennedy administration had a policy of assured destruction — the ability to destroy the Soviet Union in retaliation for any nuclear attack. Hawks, though, thought that deterrence might very well fail — and the United States should be prepared to win a nuclear war. They lampooned settling for a nuclear deterrent by calling President John F. Kennedy’s approach assured vulnerability or mutual assured destruction, to emphasize the point that limiting ourselves to a retaliatory capability meant accepting vulnerability to Soviet missiles.

President Trump wouldn't actually press a red button to launch a nuclear attack. This is how the process would work. (The Washington Post)

But in one of those perverse repurposings that are common in language, most people thought: Yeah, that’s an apt description of the nuclear age. I mean, it is sort of crazy, but then again basing our security on the permanent threat of nuclear holocaust is fairly crazy to begin with.  And the alternative — the notion that we could arms-race ourselves into a position where we might plausibly “win” a nuclear war was insane.

At one of the most dangerous moments of the Cold War, one of President Ronald Reagan’s advisers, T.K. Jones, tried to persuade a reporter from the Los Angeles Times that nuclear war might not be so devastating if more people dug bomb shelters in their backyards. “If there are enough shovels to go around,” he told Robert Scheer, “everybody’s going to make it.” That mollified no one. Almost a million people eventually turned out in Central Park to demand an end to the arms race. If nuclear weapons mean anything, it is that vulnerability is both assured and mutual.

Among the people Jones failed to persuade was, famously, Reagan himself. Reagan certainly said and did things that alarmed plenty of people during the Cold War, including referring to the Soviet Union as an “evil empire” and joking on a hot mic that “the bombing begins in five minutes.” But he also seemed genuinely alarmed at the prospect of nuclear war and could not believe that anyone in Moscow thought he was capable of starting one.

Neither Trump nor Kim is crazy, political rhetoric notwithstanding. Trump has, on occasion, spoken movingly about the power of nuclear weapons and the influence of his uncle, who was a professor of engineering at MIT. A younger Trump even spent a period lobbying in the media for an appointment by Reagan to replace Paul Nitze in negotiating an arms agreement with the Soviets. As for Kim, he wants to save his skin — he sees nuclear weapons as a guarantor of his survival, not a route to suicide.

President Trump's political rhetoric on North Korea has differed from before he declared his candidacy to now. (Taylor Turner/The Washington Post)

And yet, for deterrence to fail, neither Trump nor Kim have to be insane or suicidal. They merely have to be the flawed human beings that we all are. North Korea has made it clear that it will use nuclear weapons first against U.S. forces throughout South Korea and Japan if it thinks an invasion is coming, in a desperate effort to stave off the overwhelming power of the United States. Trump has talked about killing Kim and seems to be willing to improvise nuclear threats with little or no discussion. I don’t think Trump or Kim wants a nuclear war, but I do think they could blunder their way into one, with each giving the other the impression that war is coming, and with military advisers who will argue that it is better to go first rather than risk not going at all.

There is, of course, something to be said for the near-term benefits of nuclear deterrence. After all, the horrors of World War II ought to have been enough to show us the ultimate folly of resorting to ever larger amounts of violence to settle political disputes, rather than serving as the excuse for a more destructive second one. Perhaps American and Soviet leaders would have blundered into a third world war without the threat of nuclear holocaust to hold them back. That’s certainly why the United States keeps nuclear weapons and North Korea has sought them.

But whatever we may wish to say about nuclear deterrence, we must also ask whether we think that our luck will hold forever, and whether every leader who comes to possess nuclear weapons will be transformed by the awesome power of these weapons. Reagan certainly was. He came to see nuclear deterrence as an ultimately evil bargain and came very close to eliminating U.S. and Soviet stockpiles with Mikhail Gorbachev, before falling just short, in Reykjavik.

If you prefer the optimism of Reykjavik to our current moment, or you worry that Trump and Kim may destroy us all, then you don’t believe in nuclear deterrence. You think that we must eliminate nuclear weapons before deterrence fails. Maybe not today or, as President Barack Obama used to say, in his lifetime. But you know that, sooner or later, our luck will run out — that we must eliminate nuclear weapons before they eliminate us. If the sight of Trump or Kim with the bomb disturbs you, then you believe in nuclear disarmament. That, or you believe in shovels. Lots and lots of shovels.