Japan was an early leader in the global trend of rapidly aging societies. It was the first country in the world to reach a median age of 40, back in 1998. In 2023 Japan still features the world’s highest median age for any large country – at 49, compared to the global median of 30 – and just over 30% of its population is aged 65 or older. This level of aging is unprecedented in human history, but almost two decades after Japan reached “super-aged” status, roughly two-dozen other countries have now reached that stage of 20% or more of their populations aged 65+, with many more expected to join this super-aged club later in the 2020s. Thus, Japan’s responses to how it has addressed challenges related to rapid aging are especially interesting for the clues they may offer to how other states adjust to super-aged status and how these changes might affect the broader security environment of the Indo-Pacific.

Japan became the world’s first super-aged global power in 2005. And yet Japan underwent what I described in an earlier work as a “security renaissance” in the decade that followed from 2006 to 2016 (Japan’s Security Renaissance, Columbia University Press, 2017). In Japan’s latest national security strategy document (December 2022), released just as Japan’s 65+ population hit 30%, even more robust approaches to miliary security are introduced, including the planned development of “counter-strike capabilities” to respond to increasing concerns about missile threats, especially from North Korea and China, and the near-doubling of defense spending to reach the NATO standard of 2% of GDP by 2027. What Japan’s military planning in the past nearly two decades shows is that previous assumptions about the effect of aging on security need to be revised due to new types of security threats (including so-called gray-zone conflicts), new technologies, and actual experiences with rapidly aging societies worldwide.

A decade or so ago, when the emergence of rapidly aging and shrinking populations was only beginning to enter public consciousness, a number of scholars advanced an idea that the emergence of older societies with fewer children would lead to more peaceful international relations. At that time, only Russia and Japan among major powers had experienced population shrinkage as a result of low birthrates and only Japan had reached “super-aged” status. Since that time, “aging power” Russia has invaded its neighbor Ukraine and an aging China has continued its sharp increase in military expenditures despite its population having begun to shrink due to its own rapid aging. South Korea and Taiwan also have increased defense spending markedly and implemented new national defense strategies to adjust to their low birthrates that have resulted in roughly half the number of military conscripts than two decades ago. In short, the security environment that has emerged in an aging Asia is far from the “demographic peace” idea that many had predicted.

The situation would be worse for US allies such as Japan if they were the only ones facing this demographic challenge, but security rivals China and Russia also face similar demographic concerns (though in their own unique ways and generally on a later timeline). Also, some US allies and partners in the region have more youthful and growing populations, such as the Philippines and Quad-member India, with Australia and Singapore also continuing to have growing populations due to robust immigration. The regional "arms race" that many observe today is in part a result of many aging territories in the region spending more to shift the composition of their armed forces due in part to challenging demographics, particularly countries that previously had relied on cheap, conscripted military forces like South Korea and Taiwan (and, to some extent, China).

The strategy that Japan’s leaders have developed to address what its December 2022 National Security Strategy describes as “the most severe and complex security environment since the end of WWII” goes against what observers expected of an aging society with a shrinking population and serious fiscal challenges. Rather than looking inward, Japan has expanded the number and depth of security partnerships with other states and has put into place a plan to increase its own military capabilities in numerous significant ways.

It is also important to note that many regional economies are predicted to grow substantially even with shrinking total populations: fewer workers do not necessarily mean a smaller economic size. In many cases this is because in still-developing economies retiring labor is being replaced by better-educated and healthier younger workers – in addition to new technologies and more automation. China will likely see a substantial boost in productivity from a leaner, younger workforce; Japan less so since even its older workers already were highly educated and healthy, but Japan too has seen continued total GDP growth despite experiencing population shrinkage for over a decade and is expected to continue to grow its economy despite an even faster shrinking population.

My research finds that the rise of numerous types of new, gray-zone conflicts also means that a wider range of people (and machines) can be used to address different sorts of security challenges. More than ever, militaries are seeking to recruit different types of people to address specific concerns -- including a bigger role for those with skills useful for cyber defense. The shrinking pool of potential recruits due to a smaller working-age population also necessitates more flexible thinking. Demographics are not the only driver of more flexible recruiting practices, however: we see a similar trend in the US and Chinese militaries, for example, even though there is not (yet) the same level of demographic urgency to change established recruiting practices in those countries. When pilots can fly planes from trailers in homeland suburbs rather than deployed abroad and some of the most urgent threats states face are in the cyber domain, it opens the door for a much wider range of people to contribute to national defense. It also affords a greater role for security partners from other countries.

Given persistent shortfalls in recruiting and retention in Japan’s Self Defense Forces and the future demographic pinch ahead, there is no planned increase in the total number of military personnel in Japan’s 2022 National Defense Strategy. Instead, a wider range of civilians and technological offsets are envisioned while new efforts to maintain even the current force posture are put into place. Even with an ambitious list of new initiatives, it will be a challenge for Japan to maintain its current force level of roughly 230,000 actual military personnel given Japan’s rapidly aging and shrinking population – just as it will be for Japan’s close neighbors South Korea and Taiwan. Potential shortages of skilled workers in the defense sector more broadly also are concerning given Japan’s goal of increasing domestic production of military equipment. Japan’s 2022 National Defense Strategy devotes several pages to reinforcing Japan’s defense production base but does not highlight labor shortages as a challenge in that area, a shortcoming that should be addressed.

There has been substantial research and policy discussion focused on how Japan’s declining birthrate might be reversed as Japan’s demographic challenges become more widely felt. This should indeed be one goal for a country that is projected to shrink to its 1965 population size by 2050 and will continue to shrink further unless its birthrate increases (or immigration is substantially increased). For the next two decades, however, Japan’s defense planners must work with the existing population as well as potential international partners: anyone who might join the military or work on Japan’s cyber-defenses in the next 20 years has already been born.

Despite many challenges that arise from the rapid aging phenomenon, Japan has shown an impressive range of innovative approaches to address these challenges including increased automation, outsourcing of some defense roles, improving efficiency and streamlining procedures, and increasing/deepening international partnerships. All of these approaches will need to be further employed to address the increased aging and population shrinkage on the near-term horizon. Japan’s long life expectancy combined with its low birth rate mean that the Japanese population will continue to age rapidly in the decades to come, with a projected median age of over 54 by 2050 and more than 38% of its population aged 65+. This great achievement in health and longevity will pose further challenges. Japan’s experience to date, however, also provides a useful template for how other states in the region and worldwide also could maintain a strong defense posture despite the challenges posed by rapid aging.