There are two reasons not to be so nervous about North Korea’s recent tests of missiles and nuclear explosives. First, nuclear deterrence—the theory that Country X won’t fire nukes at Country Y if Country Y has nukes it can fire back—works. In the annals of international relations, there are fewer theories that have a better track record than this one. Second, we have thousands of nuclear weapons—stationed worldwide, on land, at sea, and in the air—and there’s no way Kim could launch an attack on us without facing an annihilating retaliatory blow.

The same logic that has prevented nuclear war for decades will work on Kim Jong-un.