I was listening to a CFR podcast of a special conference call on North Korea’s nuclear weapons test yesterday during my much longer than usual commute. One key part of the discussion centered around Japan’s response to the nuclear test and missile launches. Japan, it seems, is taking steps to improve its military capabilities in response to North Korea’s actions. Even the most extreme option–Japan going nuclear–seems to be lurking near the table. The conference call participants saw China as a key to the North Korean situation, with greater action possible this time in part because China wanted to keep North Korea in check to mitigate any potential Japanese military expansion.

Recently, I supervised an excellent MA thesis that examined military policy among great powers in Northeast Asia in response to China’s ongoing military modernization from a neo-realist perspective. The question driving the thesis was that China, as the rising power expanding its military capabilities through its modernization program might provoke balancing behavior from the other great powers of the region. The conclusion was that there was no classic balancing behavior, rather there was some buckpassing and “hedging.”

This raised an interesting puzzle. North Korea is nowhere near a great power. While they do have a large military, it old, outdated, and oriented toward the DMZ. They do have WMD and missiles, though the missiles are highly unreliable. China is a rising great power with a highly capable military that is increasing its ability to project power.

For Japan, a state that has constitutionally limited its military power to self-defense missions and has a deep aversion to nuclear proliferation, to consider a military build up is a big deal. For the notion of nuclearization to even be broached is quite a major step. Good old balance of power theory might lead one to suppose that it would take the rise of a significant challenger to push Japan in this direction.

But my guess is that it would ID China as such a challenger well before it would tag North Korea.