While the essay (Link) is a decent review of what Japan has done -- and what Japan has done is not bad -- what I found most interesting was the last paragraph:
What should be clear is that, despite talk of Japan's decline, it is actively engaged in the security and diplomatic spheres in an effort to promote regional stability. Continuing this engagement will depend on Japan’s ability to overcome two domestic challenges: demographic implosion and mounting public debt. Both problems will have adverse effects on Japan's economy and the military, which will constrain defense spending and an ability to fund/expand security and diplomatic initiatives. Both require adept political leadership to rectify. If Japanese leaders can overcome these challenges, it would mean continuing opportunities to provide crucial resources to security partnerships and initiatives as well as leadership toward developing institutions and initiatives. If Japanese leaders fail, however, regional security will suffer as the gap left by the withdrawal of Japanese military capacity, expertise, and resources as well as diplomatic vision and commitment to multilateral institutions/initiatives will be difficult to replace. It is in this light that, if we envision a world without Japan, we can see it as being a consequential power.The above is flatulent nonsense. Under no conceivable (pun unintended) scenario can Japan's population decline be arrested. The cohort of women in their peak childbearing years is simply too small (see graph here).
As for mounting public debt, given the reality that the Abe administration's answer to Japan's economic malaise is not structural reform but a stimulus package funded by construction bonds, talking about reductions of Japan's debt is a purely philosophical exercise. Indeed, the only method of debt reduction under discussion is default. (Link)
Contrary to Dr. Hornung's assertions, the limits on Japan's engagement in regional and global security cannot be the demographic shift ("implosion" is hyperbole) or public indebtedness. If they were, then the argument would already be over. China's and to a lesser extent North Korea's actions and the government's framing of new Japan Self Defense Forces security initiatives are the two most significant factors -- and will be for the foreseeable future.
* Given the percentage of the world's elites educated in United States universities, writing for American elite audiences is globalization-on-the-cheap.