This often gets lost in portrayals of Kim Jong-un, North Korea’s leader, as a wild-eyed lunatic. But while Mr. Kim might be eccentric, he has repeatedly proven himself to be rational. Ruthless and morally reprehensible, but rational. And no rational leader invites national suicide, which is all Mr. Kim would achieve by provoking a war.

The United States has its own nuclear weapons, as well as overwhelming conventional military superiority, to deter North Korea. Historically, deterrence works. It’s how the United States has lived for decades with the threat of Russian and Chinese nuclear weapons.

(4) China might not be able to solve the North Korea problem.

American leaders have, since North Korea’s nuclear program began, invested their hopes and their strategies in China. If only Beijing were properly motivated, the conventional wisdom goes, it could rein in its North Korean ally and neighbor.

But it may be time to consider why this strategy never seems to work.

North Korea is convinced that giving up its nuclear weapons would invite an American invasion, similar to what happened to Libya after it surrendered its own warheads. China can put a lot of pressure on little North Korea, but it’s not clear that such pressure scares Mr. Kim more than the threat of national destruction.

In any case, North Korea and China have been increasingly at odds. North Korea’s weapons tests often seemed timed to humiliate and defy Beijing. China has imposed its own sanctions in response. So while Americans sometimes perceive China as supporting North Korea’s provocations, in fact the opposite is often true.

(5) North Korea has shown it can endure extreme economic punishment.

Even the most severe sanctions might not be able to impose anything that North Korea hasn’t survived before. In the 1990s, the country’s economy and food supply collapsed simultaneously, setting off a famine that killed up to one-tenth of the population.