To paraphrase former U.S. President Ronald Reagan, one could say to North Korea's leader Kim Jong Il, "There you go again." This isn't the first time the despot has tested nuclear devices, launched missiles, and threatened his enemies. Nor will it likely be the last.

His latest antics have led to a well-rehearsed flurry of activity aimed at coming up with sanctions to force Pyongyang to alter its behavior. Yet much of the diplomatic ballet around new UN resolutions, discussions of calibrated punishment, and other calls for action actually fails to reflect the core realities of the situation.

It is often argued that China is caught between a rock and a hard place. On the one hand, North Korea's weapons of mass destruction program is detrimental to Beijing. It fuels greater U.S.-Japan military cooperation, strengthens American and Japanese arguments for beefing up their military capabilities in Northeast Asia, and creates geopolitical instability at a time when the Chinese Communist Party wants order at home and abroad.

On the other hand, if China were to cut off trade and aid to the North, it could bring down the regime. The Götterdämmerung of Kim Jong Il and company could well include domestic disturbances or war with South Korea. Even if North Korea were to disappear peacefully, China might not find itself better off. Unification could destabilize the entire peninsula, given South Korea's inability to absorb the more than 20 million semi-starved Northerners into its economy and society.

Moreover, China could find itself bordering a U.S.-leaning liberal democratic polity, which is not an ideal outcome for Beijing. Finally, though the Chinese and North Korean communist parties are dissimilar, the Chinese leadership would probably not see the demise of an Asian communist state as a good omen.

Thus, the argument goes, Beijing is unwilling to put "real pressure" on Pyongyang (unlike Washington, Tokyo, and now Seoul since the Lee administration took over), hence making it impossible to implement a credible sanctions regime.

But the hidden truth, often forgotten, is that Japan and the United States are in the same boat as China, and South Korea even more so. None of these countries wants North Korea to disappear. For South Korea, the demise of the North would force Seoul to suddenly bear the burden of managing the North. To put it in an American perspective, it is as if there were well over 100 million Cubans, with Cuba even poorer than it is today, and upon the passing of the Castro brothers the island became the Union's 51st state.

The end of North Korea would bring new challenges for Japan and the United States as well. Preventing the total collapse of a suddenly destabilized Korea would call for a massive aid package and a complex set of diplomatic negotiations with China and the new Korea—not exactly the easiest rescue plan to sell to a Congress that can't even vote on a U.S.-South Korea FTA (KORUS). In the Japanese case, some observers are worried—probably irrationally—that a flood of refugees would reach the archipelago.

There is therefore an enormous limit to what Japan, South Korea, and the United States could do even if China agreed to follow their lead. If trade and aid were cut off—including flows from China—Kim would not lose sleep letting some of his people starve, but fairly quickly the allies would feel morally obliged to prevent such suffering. Stronger sanctions could indeed bring him down, but that is the outcome everyone wants to avoid. Other forms of sanctions could have some effect, but the truth is that options are very limited.

The best reaction to the DPRK's WMD program is to maintain a high level of deterrence by making sure that the United States has the visible ability to crush North Korea should Pyongyang choose the path of war. Deterrence worked against far more dangerous enemies—first and foremost the Soviet Union—and it has worked with North Korea for decades. Nukes and missiles do not radically alter the equation. The second task for Japan, the United States, and South Korea, along with China, is to think about how to manage unification if the regime in Pyongyang collapses, which could be tomorrow or many decades from now.

Robert Dujarric runs the Institute of Contemporary Japanese Studies at Temple University Japan Campus. He is a former Council on Foreign Relations (Hitachi) Fellow in Japan.