Kim Jong Nam, the eldest son of North Korea's former leader, Kim Jong Il, was recently murdered. He had been groomed as heir apparent to his father for many years before being sidelined and sent into exile. Since about 2003, he has been absent from the country's politics. The title of heir apparent, and the leadership of North Korea, went to Kim Jong Nam's half-brother, Kim Jong Un.

Then, this week, the shocking news surfaced that Kim Jong Nam had been murdered by assassins wielding poison needles. It's not clear who is behind the murder, but South Korea says the assassination was almost certainly ordered by Kim Jong Un. If that's true, the murder may be a signal that North Korea's regime is close to collapse. And if that's the case, we should all be scared like hell.

Trying to understand what's happening inside North Korea makes Kremlinology look like an exact science. There's very little we know for sure about North Korea's regime, and what we do know is open to interpretation. But we do know a few things. For example, we know that, since taking power, Kim Jong Un has taken an even more confrontational stance towards the outside world than his father did. He has stepped up the country's nuclear program and antagonized the West with missile launches. His behavior has even angered China, North Korea's main patron.

The other thing we know Kim Jong Un has done is engage in a series of purges. The world was stunned when Jang Sung Taek, a four-star general and essentially the regime's number two guy, and the man who ensured a smooth handover of power between Kim Jong Il and Kim Jong Un, was executed. The Kim regime also had members of Jang's extended family killed. Another shocking purge victim was O Sang Hon, deputy minister in the Ministry of Public Security, the country's police.

If you're a faction within North Korea's regime, and you're alarmed by Kim Jong Un's rate of purging, you might think about striking first, effecting a coup, and removing him. What's more, North Korea's entire propaganda apparatus for many decades has revolved around the Kim family's mystical claim to power — if you were to envisage a coup, it might be useful to have another Kim lying around to use as a figurehead. Enter Kim Jong Nam.

If you're a leader who wants to hold on to power, and you fear that some group in your regime might launch a coup and try to put your estranged half-brother in your place, you might try to cover your bases by having that brother assassinated, just in case.

Running a reign of terror is tricky business. Don't kill enough people and you might be perceived as too weak, and be killed yourself. But if you kill too many people, some will start thinking they're next on your list, and they will gang up on you. This is what happened in the Soviet Union upon Stalin's death, when Lavrentiy Beria, the infamous head of Stalin's secret police, made a bid for power. Unlike Stalin, for whom killing was just business, Beria was a sadist who joyfully relished torture, murder, and rape. Beria very briefly ruled the country, but the rest of the Politburo had absolutely no doubt that Beria would eventually have them all tortured and killed. So they killed Beria before he could kill them.

The same thing could happen to Kim Jong Un. It's possible that he has stepped on this treadmill of purges and paranoia, and the killing of his own half-brother is evidence of that.

Maybe I'm wrong. Maybe Kim Jong Un will die of old age, still in power, like his father and grandfather before him. Or maybe he will be taken out, but in a relatively bloodless coup, and be replaced by some other strongman who can hold the country together. Or maybe taking out Kim Jong Un will lead to the collapse of the regime.

But let me be clear: The question is not if the North Korean regime will collapse, but when. And this ought to alarm us. Such a collapse would be a humanitarian disaster. North Korea's population is around 24 million, the vast majority of whom are malnourished and utterly unequipped for productivity in any kind of non-communist economy. Many millions of refugees would flee in every direction, pouring through borders, overwhelming China and Russia's poor governance, and almost certainly straining South Korea. Still tens of millions more people would remain in North Korea and would have to be somehow taken care of.

And then there is North Korea's active weapons of mass destruction program to consider. We know very little about this program, but we know it includes nuclear weapons. North Korea also has a massive arsenal of conventional weapons, most of which are dilapidated, but we have to assume some are still functional. What would happen to those weapons in the case of a regime collapse? Do you think a North Korean general would contemplate the possibility of selling a nuke to ISIS but then refuse because he has such respect for human rights and the welfare of the human family? Not likely. Really, the possibilities for horror on a world-historical scale are fractal.

Even in the face of these terrifying realities, the world outside North Korea seems woefully unprepared and complacent. Whether it's China, South Korea, or the U.S., the world's strategy towards North Korea seems to be to cross fingers, close eyes, and hope for the best. I have previously argued that the world should effect a controlled demolition of the North Korean regime, so that what may be controlled can be. I realize that this is an "extreme" position, but my fear is that few contemplate with enough seriousness how truly extreme an uncontrolled collapse of the North Korean regime would be. Indeed, North Korea's collapse is coming — perhaps sooner than we realize — and we are unprepared.