© PoliticoKim Jong Un
"The more you approach infinity," the French novelist Gustave Flaubert wrote, "the deeper you penetrate terror."

So it is with Kim Jong Un, already the most dangerous man in the most precarious nuclear state in the world. After the swift execution this week of his uncle-cum-regent, Jang Song Taek, he has become even more dangerous. Kim has boxed himself into a corner where it is hard to fathom a peaceful future for either his family dynasty or the country he rules.

The full implications of this bloody purge will reveal themselves over time as additional disturbing revelations seep out. But Kim's murderous act leaves an indelible stain. Global risk is now heightened, as the slaughter at the top of Pyongyang's pyramid locks Kim into a reign of terror, with consequences that threaten the security of the entire region.

There is little doubting Uncle Jang's "acts of treachery." To be sure, some of the myriad charges against Jang, listed in a remarkable North Korean news release, belong in the theater of the absurd (underselling his nephew's stunning achievements, presumably a water park in East Pyongyang and a ski resort set to open at month's end). But there was indeed skullduggery afoot. Clearly Jang was guilty of building his personal power, a threat to the 30-year-old Kim, whose bloodline entitles him, not the man who married his aunt, to claim the mantle of his father, the late "Dear Leader."

The abrupt and brutal manner in which Kim dispatched his uncle highlights a disturbing degree of cruelty and erratic behavior. South Korean National Assembly Chairman of Information Seo Sang-gi said he was told that Jang and his subordinates were executed with machine guns and flamethrowers. Kim's challengers may be silenced for now, but their ranks are undoubtedly on alert as to what must be done - a fact that can only add to the young tyrant's paranoia.

Jang's execution is alarming for reasons beyond what it says about Kim's state of mind. He was not just Kim's uncle; he was a powerful figure inside the regime, and many saw him as an advocate of gradual, Chinese-style reform. That made him a key interlocutor for Beijing, because what Chinese officials fear most about North Korea is not its nuclear weapons or its grandiose threats to turn Seoul into a "sea of fire," but a collapse of the North Korean state that would send millions of starving refugees streaming across its border. China's plan for a soft landing appeared to include a combination of personal cooption (Jang was reportedly deep into Chinese pockets) and hard infrastructure (investments in special economic zones and resource extraction). Now, that dream has died with Uncle Jang.

Indeed, a complete economic meltdown seems inevitable. Kim's relentless determination to pursue nuclear weapons, coupled with his ruthless brand of authoritarianism, will deter foreign investment and accelerate North Korea's decline. Despite hopes that his Swiss education would give him a more Western outlook, Kim has failed to follow through on any significant economic reforms. His concern for domestic enemies will ensure that yet more resources are poured into security and defense - a vicious downward spiral from which North Korea might never recover.Sitting atop a failed economy and a closed society, maintaining order through terror and a police state, Kim is running out of moves. In the span of two years, his image has lurched from that of a youthful, reform-minded man of the people and caring father to the worst kind of medieval despot. It harkens back to Choson Korea, where killing competing royal family members was not uncommon. There is even an historical precedent in which a young 15th century ruler, King Danjong, was overthrown and eventually killed by his regent uncle. Five hundred years later, North Korea stands as a paean to pre-modern barbarity. Execution instills a sort of order and discipline, at least on the surface. But in the 21st century, it is a prelude to bitter demise. Morality aside, the reason despotism has fallen out of fashion is because there's little future in it.

But North Korea, already the world's most repressive state, could get much worse in the interim. As Kim fears for his absolute power and survival, he is apt to plunge his country into full totalitarian terror, with momentous consequences that won't be easily contained. North Korea's retrograde technology and its bizarre propaganda may make us laugh, but it is also a heavily armed nuclear state with a leader who is losing contact with reality. That ought to concentrate some minds in the White House.

The question is what to do now. After Jang's execution, the Obama administration needs to inject vigor and fresh thinking into its North Korean policy, which has largely been to ignore Pyongyang's tantrums or simply pile on more sanctions. Instead of being reactive, it's time to look ahead and plan for the worst.

A new U.S. policy needs to be comprehensive, not simply focused on ridding the world of North Korea's nuclear weapons. That means working with China, recognizing that we share a common interest in peace, and that we need to be debating how to achieve long-term stability and not just next steps toward denuclearization. With the South Koreans, we need to step up planning for any number of scenarios, from surprising new provocations to a palace coup to the sudden collapse of the Kim Dynasty.

Kim's end is virtually inescapable. Only the timing is in question - but Jang's execution is a reminder of how quickly it might occur. Third-generation dictatorships are inherently problematic. Removed from their initial source of legitimacy, they must be measured by their performance. And in North Korea's case, being surrounded by prosperous economies makes that impossible without opening up the country to economic liberalization. In the information age, more members of the elite will know that the regime must go.

The stakes are enormous. The Obama administration can no longer relegate North Korea policy to the back burner. The end of the Kim Dynasty is approaching, and with it the demise of North Korea could quickly follow. If ever there were a time for daring, muscular multilateralism, this is it.

Patrick M. Cronin is senior director of the Asia-Pacific Security Program at the Center for a New American Security.