It's reassuring to know that when the nuclear apocalypse wipes us out, it will be triggered by something most of us could code ourselves on a rainy afternoon.
Or just a dumb mistake. When the rhetoric ratchets this high, the scary idea is that one party or the other may actually believe it.
That's what happened in the 80s during the Cold War. We discovered belatedly in the 90s that Soviet president Andropov had already concluded in the early 80s that the US had won the Cold War, that the US could launch a successful first strike (with what he as an old Soviet WWII hardliner considered "acceptable losses"), and that President Reagan would be the American to do it. Andropov believed in his heart that Reagan would launch a first strike at any moment.
When we discovered that, we looked back on some of his rhetoric during that period and reflected on how Andropov had reacted so vicerally to every anti-Soviet remark by Reagan.
And then, it came to a head with the US exercise ABLE ARCHER 83. The various US nuclear forces each held their own annual nuclear war exercise, but that year some smart guys decided all the US nuclear forces should have a single big exercise, fully coordinated and, shucks, let's even bring in the National Command Authority (the president played, as I recall, by Warren Christopher).
So we had the biggest nuclear war exercise ever--not realizing how edgy the Soviets were.
I was on the Strategic Air Combat Operations Staff (SACOS) in the SAC Hq Underground Command Post at the time. When we got to the point that we were ordered to execute the Major Attack Option ("Fire everything!"), the exercise was over for us. That's because we estimated 25-30 Soviet warheads were targeted for the spot we sat.
It was just past noon. I went to my regular basement office to check my in-basket and planned to go home for a long nap. Then I got a telephone call: "Report back to the Underground...right away!"
I got back down there and they filled me in: The Soviets had "reacted" to the exercise. The Soviets couldn't break our encryption, but they had figured out who would be talking to whom, and it was a standard Soviet tactic to claim to be merely exercising and then actually go to war.
So when they got an indication that the execution order had been given, they started opening ICBM silos, deploying mobile nuclear forces, and flushing their boomers out of the sub bases.
You read articles about ABLE ARCHER 83 online, including a quite good Wikipedia article. But none of them mention the fact that we had four days of sheer terror. We had faith that someone was trying to talk the Soviets back from the edge, but in the SAC Underground Command Post, we were preparing for nuclear war as furiously as we could. Everything that had been an exercise before was suddenly the real deal. The generals' faces were as gray as concrete.
So in these days, the big thing that scares me is that Kim Jong Un probably does believe everything Trump says--he probably truly believes that Trump has actually made the decision to attack...it's just a matter of time. And that is dangerous. It makes it all too likely that some one over there is going to overreach, afraid of being the one who didn't react in time.