How does population aging affect national security?

A caution for the foresight and defense communities

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Ever wonder why Russia’s demographic strains aren’t keeping Putin’s aggressive ambitions in check? Whether we should expect population aging to make China more of a threat, too? Or whether population aging among the great powers gives the US an advantage? I have a new peer-reviewed article exploring those questions in the journal International Affairs in which I offer an institutionalist theory of population aging and national security. Here’s a summary for those without access to the journal (and email me if you need help accessing).

One month before I launched 8 Billion and Counting in 2022, Russia invaded Ukraine. My book was already printed, and if I’d been one of the many scholars who thought Russia’s dire demographics—intense population aging, high mortality, a shrinking population—would constrain their power projection, I could have been on the verge of looking really foolish. Instead, I looked prescient.

It me. Looking at a world of 8 billion people. Source: Getty Images pidjoe

See, I’d been closely studying the relationship between population and national security since before my time at the Pentagon in the mid-2000s and what I’d observed led me to point readers towards the importance of non-demographic factors in conditioning the effect of population aging on national security behavior. Population aging and depopulation weren’t going to automatically make Russia, China, or any other state more peaceful or more aggressive.

That’s because it's the intermediate variables that determine the effect of aging and shrinking on national security behavior, in particular (1) the rules of the game, or institutions, in each state, and (2) the responses policy makers take as structural conditions change (i.e., aging).

The key point here is that when studying the effects of population aging, researchers shouldn’t expect the experience of aging to be uniform.

Population aging is the key trend shaping today’s world. The populations of Russia, China, and Japan are already shrinking and the US, while still growing, is rapidly aging. What does it mean that all four Asia-Pacific great powers are seeing unprecedented shifts in their age structures?

Always start with institutions

Institutions structure collective behavior, and there are many to consider, like federal versus centralized structures. Familialism, a system in which a high level of family welfare care is absorbed by the state, shows us that although there is always a cost to population aging, it is not always borne by the state. Those who thought that by now China would have vastly expanded its welfare benefits to older people and have gone broke missed an important political factor. It is not that aging has no cost, it is that the cost is different in different settings. There are always winners and losers.

When institutions—the rules of the game—concentrate decision-making in the hands of one leader or a small group, as in non-democracies like China and Russia, those leaders’ preferences and perceptions become important factors that trump the fiscal and personnel strains of an older age structure and permit a more aggressive foreign policy. I’m really concerned about the ability of democracies to remain resilient in the face of aging, the US in particular. US institutions discourage the type of long-term planning needed in the face of fundamental demographic shifts.

There’s a role for policy, too

But our analysis can’t stop with institutions; we have to map responses, the policy actions taken. A little structure, a little agency. Of course, the two are connected, as the ability to make policy is constrained or facilitated by a country’s institutional setting. Just think about how hard it has been for France to raise retirement age in an institutional setting where the people effectively pressure politicians.

People take part in a demonstration in Marseille on March 7, 2023, as part of a nationwide day of strikes and protests called by unions over the proposed pensions overhaul, which include raising the minimum retirement age to 64 from 62 and increasing the number of years people have to make contributions for a full pension. (Photo by NICOLAS TUCAT/AFP via Getty Images)

There’s a lot leaders can do to adapt to aging and be resilient in the face of this change. Smart leaders don’t just sit around and let population aging wash over them without doing anything (like they might, say…climate change?). Quite the opposite. Aging Asia–Pacific powers have instituted a host of policies that respond to or adapt to their demographic shifts, like changes in military recruiting practices and immigration policies. By the way, when it comes to discussions of recruitment issues, there’s way too much emphasis on the overall size of the recruiting pool. That 77 per cent of Americans aged between 17 and 24 years are unqualified to serve in the US military, and only one in 11 of those eligible has a propensity to serve, points to room for policies completely outside expanding the total number of military-age Americans. Higher fertility rates would not help the US overcome these obstacles.

Technology is a key adaptation. Unmanned aerial vehicles (drones) and artificial intelligence (AI) can take the place of ‘boots on the ground’ to some extent. Even though technology isn’t a perfect substitute for manpower, as automation increases—not just in warfare, but across the economy—it will dilute the impact of demographic changes even more. And my research increasingly points to the importance of health in aging populations. Japan’s overall population is shrinking while the US population is growing, but Japanese live long, healthy lives and work on average until age 71. That’s not the case in the US.

Dear foresight community…

Here’s why this institutional perspective on aging matters: The national security strategies being developed today should be built upon an accurate view of the horizon. If we don’t account for the ways institutions mediate demographic change, we risk severely under- or overestimating the capabilities and intentions of allies and adversaries. Policy makers may also miss the chance to make policy changes in non-military areas that could increase national power, such as extending working lives through reforms to labor market rules.

We have to move past the dichotomy and oversimplification that often characterizes discussion of demographics—aging is either ‘good’ or ‘bad’; aging either fosters peace or incentivizes conflict—because no demographic trend has a predetermined outcome.

We can’t make a definitive statement about whether aging leads to greater peace or instability. Instead, we need to focus on learning under what conditions and in what ways aging matters for national security outcomes. It’s not a question of whether aging states can still project power, rather, it’s a question of how aging displaces human, economic, and other forms of capital that would have been used elsewhere, particularly in the projection of power.  And it’s not a question of whether there will still be war in an aging, depopulating world. Rather, we need to understand what war—or conflict in general—looks like in an aging, depopulating world. The conflicts of the present look similar to the conflicts of the past, but technological advances may continue to change the nature of warfare in ways that dilute the personnel challenges in aging populations.

A lot of questions remain unanswerable at this stage:

• Can the four Asia–Pacific powers serve as models for other aging states since the next group of states to age—which include North Korea, Thailand, Cuba, Brunei, Colombia, Iran, Vietnam—includes more non-democracies than the early group? Almost all of the first states to age were democracies. Are some ascribing the pacifying influence of democracy to age structure?

• Is the relationship between population aging and national security non-linear? Does it depend on the degree of aging and the speed of the demographic transition? Middle-income countries such as India and Thailand are seeing age structure changes twice as fast as Western European states did.

• Does a demographic limit exist, some threshold of aging and depopulation beyond which a nation is unable to project power at all or even defend itself?

Dear fellow scholars…

We have to be careful how we study population aging and security. Interstate wars are uncommon, particularly among great powers, and they’ve only been aged for a maximum of 20 years so large-n quantitative studies aren’t necessarily useful. Analytically, it is less interesting when a state that does not usually engage in conflict at all also does not engage in conflict when its society ages. It is more interesting to know whether more conflict-prone states, or those that typically project power or challenge the status quo, are continuing their hawkish behavior as their societies age, which is indeed what my International Affairs article reports.

Estelle Metayer’s Substack is all about finding the kinds of strategic blindspots I’m talking about here.

I traveled so much this summer. Upstate NY was a respite from the burning heat of the South.