Nor does the ROK have any claim to a continued presence of American troops after reunification. Continuation of the alliance might be in Seoul’s interest, but it certainly is not in America’s interest. Indeed, today the South is capable of providing for its conventional defense. With the U.S. republic essentially bankrupt as it faces an entitlements tsunami, it cannot preserve every existing defense commitment simply because they exist. Of course, even a reunited Korea might feel uncomfortable next to an overwhelming China, but America’s military policy should reflect domestic security, not foreign charity. Moreover, the ROK has options, including building its own nuclear deterrent (perhaps preserving weapons acquired from the North) and working to improve its ties with Japan as well as Russia and India as possible counterweights to the PRC.

Mile by mile and person by person, North Korea is the most destabilizing nation on earth. The small, poor and isolated country is building nuclear weapons and intercontinental missiles. Americans who once felt invulnerable are worrying about the possibility of nuclear war.

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While most everyone agrees that something must be done about the Democratic People’s Republic of Korea, there is no consensus on what to do. Military action could trigger a destructive war, sanctions might do nothing or trigger regime collapse, and negotiations aren’t likely to result in the Korean Peninsula’s denuclearization.

So the present crisis appears insoluble. It’s hard to look into the future when today looks so grim: an unpredictable authoritarian regime bent on becoming a nuclear power and that can be stopped only through the very war which Washington has spent more than sixty-four years deterring on the Korean Peninsula.

Yet even as the present threatens to overwhelm, the DPRK’s neighbors should look to the future. What happens if the Kim regime collapses, the North Korean state implodes, and/or the North disintegrates as a nation?

The common assumption in all these circumstances is that there would be reunification, which in practice means the South would “swallow” the North and the resulting state would simply be an enlarged Republic of Korea. That’s an outcome most South Koreans and Americans—and probably Japanese—desire, though there may be a surprising number of Chinese and Japanese who don’t want to face a united, empowered competitor. For the latter, a divided Korean Peninsula is ideal, even if they would prefer a different kind of regime in the North.

Still, a negotiated reunification would be the best result, with the Korean people North and South deciding without interference how to make a common future. But there is little likelihood of that result. North Korean officials were emphatic about not wanting to be “swallowed,” when I visited the North. And it is hard to imagine the circumstance that could voluntarily bring the totalitarian communist North and democratic capitalist South into anything approaching a unified state. This is a fantasy.

But what if stiffer sanctions, presumably ruthlessly enforced by the People’s Republic of China, led to serious unrest and upheaval in the North. One possibility would be a catastrophic dynastic, regime or national collapse. Reunification might be the ultimate result, but the transition could be ugly, costly and even bloody. Imagine civil war and factional conflict, loose nuclear weapons, economic implosion and mass starvation, and waves of refugees fleeing the North and South.

The ultimate denouement might be equally messy. A South Korean-dominated reunification would not likely be as smooth as Germany’s reunion. Given the vast economic, political and social differences between the two Koreas, reunification in effect would be a “conquest,” warned Andrei Lankov, who has studied in—and written widely about—North Korea. Despite historic and ethnic commonalities, the two peoples have developed differently; even after freed from the Kim dictatorship, North Koreans likely would remain influenced by a lifetime of teaching that southerners were “puppets” of American imperialists.

Observed Lankov: “The fact is that people don’t like being conquered. You should not expect that everybody will be jumping with joy, greeting your troops, your officials, your missionaries with flowers. They are probably more likely to [be] greeted with bullets or, at least, thinly-veiled and enduring hostility.”

Even in the best case, reunification would be a long, complex and expensive process. The cost to the ROK would be huge. The influx of voters from an impoverished socialist land could transform South Korean politics. The South likely would turn inward to focus on knitting together two very different lands.

Moreover, the assumption that Korean reunification is the inevitable outcome ignores China. The People’s Republic of China is simply assumed to be a passive actor, a very large potted plant sitting just north of the Yalu River. However, Beijing would prefer not to see reunification, which could create a stronger, independent, nationalistic state on its border—one which could spur irredentist claims to Chinese territory populated by ethnic Koreans and would still be allied with the United States. Indeed, the possibility of expanded base opportunities, useful for containing the PRC, would complete China’s nightmare. Observed George Mason University graduate student John Dale Grover, “A world without North Korea would be dangerous for Beijing.”

That means the PRC might intervene to forestall such a result. Although some Western pundits have invited Beijing to invade the North to oust the Kim dynasty, that seems beyond unlikely. Almost certainly the North Koreans would fight and the conflict would be ugly. China then would be left with the unpleasant task of occupying and remaking the DPRK. It is hard to imagine the current leadership giving such an idea serious consideration.

In contrast, a faltering North Korea would provide the PRC with a better opportunity to act. If the Kim government was ousted but the system did not collapse, China might intervene, perhaps short of an invasion, to aid pro-Chinese actors and buttress or even impose a more pliant regime. Beijing could try to turn the North into a province, but that seems very unlikely: the Kim dynasty has protected the nation’s independence from its neighbors and North Koreans share the nationalism evident in the South. The DPRK might be small, but China likely would find it indigestible.

More likely would be the establishment a mini-me version of the PRC, an authoritarian North adopting economic reform while eschewing nuclear weapons—and relying on China to guarantee its security. Such an outcome seems more likely the more serious the problems facing the North. If chaos threatened, possibly overflowing the border into China, Beijing might choose to intervene militarily to restore order and create a temporary government. The PRC could retain its buffer state, but one which did not threaten its neighbors. Journalist Bill Emmott suggested a relationship in which the North lived “under a Chinese nuclear umbrella, benefiting from a credible security guarantee.”

Such an outcome would fall short of the ideal imagined in Seoul and Washington and could result in confrontation and even conflict if the allies also intervened in the midst of an imploding North Korea. Armed North Korean factions and American, Chinese and South Korean troops would be a volatile mix; an incidental clash could ignite something far more serious. The long-term consequences would be unpredictable, perhaps resulting in a partitioned North Korea and more hostile China.

Still, even the survival of North Korea under Chinese influence would be a substantial step forward. The nuclear crisis would end; conventional threats against the South almost certainly would end as well. Chinese influence would be enhanced, but would not threaten America or its allies. And the new North Korean state might evolve in a more liberal direction and ultimately join the South.

Nevertheless, Chinese military intervention doesn’t look likely and presumably would be viewed as a last resort in Beijing. Yet it is difficult to predict anything about North Korea. There are plenty of reasons to fear the unexpected and unusual. Given recent events, if a bad outcome is possible, a worse one seems likely.

At the very least, Washington and Seoul should talk with China about North Korean contingencies. Beijing has refused, to publicly do so in the past lest it cause trouble with Pyongyang, which could not be happy with other nations discussing a successor state. However, the interested parties need to ensure that however a crisis evolved, there would be no clash among their respective militaries in a mad rush to grab territory, weapons and population in the North.

If that approach didn’t satisfy, the ROK and United States could minimize the possibility of Chinese intervention by addressing Beijing’s presumed interests: the role of a reunited Korea and its relationship with the U.S. The PRC went to war in 1950 to forestall an American ally with U.S. troops on its border. Although such a presence has minimal military significance today, in an era of ICBMs, air wings and carrier groups, it would retain powerful symbolic significance. And the full peninsula could provide America with additional bases, which would be useful in any Sino-American conflict. In short, a reunited Korea allied with America would change regional dynamic to the PRC’s disadvantage. Beijing might not go to war to stop it, but would have no reason to adopt policies which encouraged it.