WARS AND instability are sometimes the result not just of population growth but also of demographic decline. Despite the overall increase in the world’s population, at a rate of around 1.1 percent every year, there are some countries or regions whose numbers are diminishing from falling birth rates, increasing death rates or high levels of emigration. This depreciation can be an important contributory factor to an ensuing state of international instability and to the advent of “Depopulation Wars” that can be waged both by and against a diminishing state. In particular, it is no coincidence that two of the most troublesome countries in the contemporary world—Russia and North Korea—have in recent years both been experiencing either significant demographic falls or the real threat of them.

Of course, there is no necessary connection between depopulation and instability. During the past few decades the populations of Japan, South Korea and, until the very recent arrival of a large number of immigrants, Germany have been in a steady state of decline born of a dwindling fertility rate among their indigenous populations: in Germany in 2015, an average of just 8.2 children were born per 1,000 inhabitants, less than a fifth of the rate of some sub-Saharan states. However, over the past half-century none of these three countries have either been attacked or sought to attack others. All also have strong pacifistic cultures. But there are other countries that lack any comparably peace-loving mentality and whose collective fears and insecurities may be considerably aggravated by a state of demographic decline. Equally, there are other states whose demographic diminution renders them vulnerable to foreign attack.

Such statements require careful definition because there are different ways in which a state’s population may “fall.” Most obviously, a population may decline in simple numerical terms, just as Japan’s population is expected to fall from 127 million in 2015 to around 88 million by 2065. But it may also diminish in relative terms: an annual increase in numbers may not satisfy the architects of economic and defense strategy, for example, if a competitor/rival has a significantly higher rate of increase.

In addition, a population may be seen to fall, even if it is not in fact doing so. Contemporary Western countries have detailed, accurate statistics about the size, and constitution, of their populations, even if these have lacunae because every census is ultimately dependent upon the cooperation of the general public. But many other countries lack or have lacked such precise data: some very impoverished countries may not have the resources to carry out such a project, while corruption and inefficiency may inhibit the accuracy of those that do so. But if it lacks such hard data, a government may think, with or without justification, that it is afflicted by population decline or indeed any other demographic change. Furthermore, it may also fear a future decline, even if it may be experiencing an increase in the immediate term. The mere risk of demographic depreciation, in other words, can cause instability and conflict.

“DEMOGRAPHIC DECLINE,” in both these narrow and wider terms, can cause instability and conflict that is instigated by a depopulating state that views a fall, or putative fall, in its numbers as a danger to its well-being. From an economic point of view, this may be because demographic growth is often associated with material prosperity, even though there are states, such as Singapore, that have stable levels of population but high economic growth. But if it feels imperiled by any such fall, then a state may try to compensate for its demographic loss.

From a more narrowly military perspective, a fall in the population can sometimes be viewed as a threat to the manpower and the economic stamina necessary to wage a war or even to keep pace with, or outstrip, a competitor or potential adversary. This association, between population and self-defense, has strong antecedents. For example, the Welsh philosopher Richard Price argued in the 1770s that a marked fall in Britain’s population endangered her livelihood and status, not least her grip over the American colonies. On the European continent, some Frenchmen took a similar position. In 1868, Lucien-Anatole Prévost-Paradol wrote a best-seller, La France Nouvelle, that urged the people of France to “go forth and multiply” in order to maintain its national grandeur at a time when “Anglo-Saxon” powers were ascendant. This expansion, he continued, would allow the French to “overflow” into North Africa, foster “a sense of pride” and contribute to “our greatness.” Such views proved enduring: on the eve of World War I, French women who had fewer than four children were deemed “no better than deserters.”

Of course, such fears are not always rational because self-defense clearly depends upon more than sheer weight of numbers and economic stamina: the quality of its arms, for example, is hugely important. Equally, some countries—notably Russia—have dwindling populations but large armies comprised of poorly paid recruits. But this may be of limited reassurance to a country that has deeply-ingrained fears of foreign invasion and attack: both Russia and North Korea, for example, have suffered numerous foreign invasions and occupations over the centuries.

One extreme consequence is that a depopulating state can use military force to seize new territory and declare the inhabitants of its newly acquired lands as its own citizens. These inhabitants are likely to share the ethnicity of the attacking state, although this does not necessarily follow: in 1871, Germany’s acquisition of Alsace-Lorraine incorporated a great many ethnic French citizens, amounting to around one third of the region’s million-strong population. Whatever their ethnicity, such an acquisition amounts to a form of “resource war” that is fought for human, rather than natural, assets.

A contemporaneous example of this kind of territorial acquisition, motivated at least in part by demographic issues, is Russia’s belligerent policy towards Ukraine, Crimea and other territories that once comprised the Soviet Union. President Vladimir Putin’s aggression towards these territories has been driven, to an important degree, by demographic considerations. This demographic factor, in the Russian mind-set, inflames and reflects a wider sense of insecurity and post-1991 decline.

RUSSIA’S STATE of demographic decline stems back to the late 1990s, when its birth rate sank to new lows under the weight of political upheaval and severe economic stress while the privileged moved overseas: within a decade, the annual birth rate fell from 2.1 births to every Russian woman, which meets the replacement level necessary to sustain an existing population, to a meager 1.20. In the Kremlin, officials were acutely aware of this shortfall. In his first State of the Nation address in July 2000, for example, Putin warned his brethren that “we are in danger of becoming a senile nation” and he has subsequently reiterated such predictions. In 2012, he argued that, if demographic trends continued, the population of Russia could decline from 143 million to 107 million by 2050. And in September 2017 the economy minister, Maksim Oreshkin, stated that Russia’s population decline was “one of the most difficult [challenges] in the world,” pointing out that over the next half decade “we are going to lose approximately 800,000 working-age people from the demographic structure every year.” He noted that, “The lowest birthrate in the country was reached in 1999 and these people are now 18 years old; they are entering the workforce. This generation is very small.”

With immigration a politically unviable alternative, the Kremlin has looked to more militaristic measures to meet this challenge. In 2014, Moscow’s annexation of Crimea, whose population stands at around 2.3 million, and its military intervention in eastern Ukraine allowed Putin to partially realize what he has called Novorossiya—a “New Russia” that would not just add to Moscow’s territory but also incorporate “tens of millions of our co-citizens and compatriots found themselves outside Russian territory.” The Russian leader has long claimed, with spurious justification and an uncertain definition, that seventeen million Ukrainians are “ethnic Russians,” and if Moscow should succeed in forging a “Greater Novorossiya,” which includes other territories, then an additional twenty-one million people would fall under its suzerainty.

There are other reasons, besides the waging of a demographic resource war, why the diminution of its population may render a state more likely to resort to military force. Russia’s annexation of Crimea and its incursion into Ukraine also compensate for the loss of prestige borne of its demographic fall or exemplified by such a decline. After the annexation of Crimea, the Levada Center, a respected polling organization based in Moscow, reported that a clear majority of Russians, 63 percent, felt that their country was a “great power.” This type of Depopulation War, undertaken to bolster national prestige, not only creates a “feel-good factor” at a time when national morale may be low but could also be calculated to attract emigrants back to their country of origin. Millions of Russians have left their homeland since the fall of the Soviet Union, and in 2015 the state statistics agency, Rosstat, claimed that 350,000 nationals had departed from the country over the preceding year alone.

But given the financial, political and (if it incurs sanctions) economic costs of war, it is unlikely that any country will initiate conflict purely to bolster its prestige. It is instead more likely to undertake risky, even provocative actions that make a clear statement to the outside world. One example is the way in which Russian warplanes “buzz” nato airspace by flying dangerously close. The number of such incidents have spiked in recent years and on one occasion, in April 2016, a Russian jet flew within thirty feet, at an altitude of one hundred feet, of the USS Donald Cook just as the American destroyer was practicing helicopter landings. But such actions can be seriously destabilizing, not least because they risk provoking an “escalation spiral,” or because of the risk of an accident.

Another possible outcome is a heightened military presence and activity in regions that have strategic importance to the outside world: for instance, in recent years the Kremlin has been building more military bases in its Arctic territories, close to disputed areas that it claims as its own sovereign soil. Such actions may be perfectly legitimate under international law but nonetheless send a clear message of belligerence and aggression that aggravate tensions with other countries.

IT IS probably more likely that ideological, one-party states will act in such a compensatory way. If the population of such a state falls, then it is difficult for government leaders to proclaim it is a “paradise on earth.” This, for example, is a claim that the Communist Party propaganda of the Pyongyang regime has long advanced. Such a “paradise” should in theory be conducive of a state of happiness and pride that engenders high birth rates, delivers a material well-being that reduces death rates and attracts immigrants rather than creating emigrants. This was one reason why, in 1937, a furious Joseph Stalin indicted the director of the Soviet Union’s official census with plotting to “make the population low.” And in North Korea in 1984, a state-run publication proudly proclaimed a low death rate: “Our nation,” it exulted, “surpassed the so-called developed capitalist nations… [which is] entirely the glorious result of the great leader, Comrade Kim Il-Sung.” It follows that any such ideological regime may try to compensate for its numerical decline in other ways.

However, a democratic state can also act in a similarly self-aggrandizing way in a bid to compensate for its diminishing birth rate. France, for example, developed a nuclear bomb not just for military and political reasons—to provide its own deterrent, independent of the United States—but to compensate for the loss of its colonies and the consequent fall in demographic power. Prior to the independence of its colonies, which began in the 1950s, Gen. Charles de Gaulle had argued that only an imperial France of one hundred million people could retain its rang (rank amongst nations). But as France’s imperial role waned, successive French governments pursued a nuclear weapons program to compensate: in 1960, the French successfully test-fired a nuclear device, prompting de Gaulle to proclaim his country “stronger and prouder” as a result.

There is another, more important, demographic reason why any country might pursue the nuclear option, thereby provoking regional arms races as well as preemptive military strikes: Any country with a diminishing population is less able, in the long term, to defend itself using conventional means. Most obviously, this is because such a state lacks the manpower to field an army of comparable size to a putative aggressor. Another reason is that it may no longer have the economic and financial weight to sustain a protracted war effort. A logical response to the challenges of a falling population is therefore to develop a nonconventional deterrent: the nuclear bomb. It also makes sense to do this without delay, while the population is sufficiently large and the economy strong enough to sustain the very high upfront costs of doing so.

North Korea’s demographic decline or, at the very least, the regime’s fears of such a diminution, remains central to understanding why it has sought to retain and develop “the ultimate deterrent.” By crossing the nuclear threshold, Pyongyang guards itself against the population falls that are likely to occur in the years ahead. Although there are few reliable statistics about the demographic reality of such an opaque state, estimates strongly suggest a long-term decline. Its population grew significantly in the 1960s before falling sharply in the 1970s and then leveling out: It is currently growing annually at around 0.5 percent. However, even this meager increase is superficial because it is made up more by people living longer than by new births: after peaking in the 1960s, fertility levels have gradually declined and currently fall below the replacement level of 2.1 children per woman.

There are other indications of North Korea’s numerical stabilization and long-term decline. In the sixty years between 1950 and 2010, its share of the entire peninsula’s population has fallen from 35 to 33.6 percent. Furthermore, independent studies have predicted that its overall population, ageing or otherwise, will experience a net decline over the next twenty to thirty years: in October 2016, the Korean Educational Development Institute claimed that North Korea’s school-age population, currently standing at 4.14 million, will decline by 90,000 by 2040. Such decline would render the North Korean regime highly vulnerable to sudden, devastating outbreaks of disease and famine, comparable to the mass starvation that decimated its population in the early 1990s. In a bid to bolster the falling birth rate and make the republic into the “strong and prosperous nation” that his propaganda boasts of, Kim Jong-un has reportedly banned abortion and birth control. At the same time, the development of a nuclear weapons program provides Pyongyang with a degree of security (not least as a bargaining chip) that would guard against long-term numerical decline. It is no coincidence that this nuclear program appears to have accelerated in the late 1990s, when the demographic impact of famine would have become fully apparent.

DEMOGRAPHIC CONSIDERATIONS also impelled Israel’s nuclear weapons program, which was instigated and developed in the 1950s on the premise that the population of the Jewish state would always be outnumbered by its Arab neighbors. At a conference held in Tel Aviv on May 5 1955, Prime Minister David Ben-Gurion argued for the development of the bomb on the grounds that “we must have superiority in weapons because we will never achieve superiority in manpower.” Others held a similarly pessimistic viewpoint and argued that regional demography would always work against Israel: in the course of crucial debates in 1961–2, Shimon Peres and Gen. Moshe Dayan both took this view, urging the rest of Ben-Gurion’s cabinet to pursue a nuclear option rather than rely solely on conventional arms. “Quality versus quantity” was the slogan of this Israeli school of strategic thought.

There are also circumstances in which demographic changes within states can incentivize a government to develop a nuclear arms program. South Africa’s white minority government, for example, initiated its program in or around 1974, at a time when the republic’s white population was—officially—stabilizing at around four million while the black population was dramatically increasing: according to official government figures that generally underestimated the black population, South African whites represented 19 percent of the overall population in 1969 but five years later this had fallen to 16 percent. In addition, the exodus of the white population also looked likely to increase as international condemnation of the apartheid regime and the risk of economic sanctions grew. In such a demographic scenario, the iniquity of white minority rule would become all the more apparent, rendering it even more indefensible before growing excoriation from overseas. However, a nuclear capability gave Pretoria a weapon that could not only fend off external aggressors but also act as a political bargaining chip to wield against the foreign critics of apartheid, most notably the United States: for example, the politically embattled regime in South Africa could have threatened to hand over its nuclear materials to an unstable successor, perhaps with pro-Soviet sympathies.

Instead of pursuing a nuclear option, a demographically diminishing country may instead invest in conventional arms whose “quality” gives it an edge over the “quality” of its rivals and adversaries: As Ben-Gurion had added in 1955, “All those things to do with science, we must do them.”

But this is also destabilizing for the obvious reason that it is likely to create an arms race. Again, Russia illustrates this danger. In January 2018, the head of the British Army, Gen. Sir Nick Carter, warned against the growing technological prowess of the Kremlin’s armed forces, claiming that the quality of their long-range missiles, artillery and capacity to wage electronic and cyber warfare had surpassed those of Western armies. “They know that demography is not on their side,” as Carter told a British defense forum, “so they are developing capability that needs fewer men—for example missiles, drones and two-man tanks.”

A DEPRECIATING state might also undertake another type of Depopulation War. This occurs when it launches a preventive assault on its adversary, calculating that the moment of attack represents its “last chance” to neutralize an enemy that will otherwise become too numerically strong to defeat. A historical example is the German attack on Russia in World War I. In 1914 German planners intended to inflict a decisive defeat on their eastern neighbor before it became not just too economically strong but also too demographically prosperous: between 1900 and 1914, Russia’s population had already grown by forty million and was expected to soon reach 200 million, while Germany’s stood at a relatively meager sixty-five million. “Russia grows and grows. She lies on us like a nightmare,” wrote Theobald von Bethmann-Hollweg, the German chancellor, shortly before hostilities began in August 1914.

There were traits of this type of demographically preventive war in Israel’s attack on Egypt in 1956. Although the architects of war in Tel Aviv, notably Ben-Gurion and Dayan, wanted to strike President Abdul Nasser’s regime before it received and absorbed a huge quantity of Eastern European arms, they were also mindful of Cairo’s growing numbers. This was not just because Egypt’s own population was growing more quickly than the Jewish state’s—Egypt has long had one of the highest birth rates in the world, standing at around 2.5 to 3 percent annually—but also because Nasser seemed poised to win the allegiance of the Arab masses outside Egypt’s own borders: with his immense personal charisma and his willingness to embrace the Palestinian cause, the Egyptian leader seemed ready to realize the pan-Arab vision that he had outlined in his writings and speeches.

Depopulation Wars might also be fought not just by numerically depreciating states but also against them. This may simply be because, as Price and Prévost-Paradol feared, a state with a falling population is less able to field an army of the quantity and quality it needs to defend itself. One historical example is the fate of Ancient Rome: it seems likely that its population began to fall from its peak in the time of Augustus, rendering it increasingly more vulnerable to foreign attack at the hands of enemies such as the Gauls and the Visigoths.

In the contemporary world, even the most technologically sophisticated armed forces still require a certain level of manpower whose shortfall renders them vulnerable to a larger, if less advanced, enemy. This is a view held by, for example, British military planners, who in 2015 admitted that falling levels of military recruitment rendered the UK “dangerously vulnerable to external aggression,” emboldening an enemy to initiate hostilities or escalate an existing conflict. Demographics help to account for this shortfall of numbers. In 2005, as the British and their allies faced increasingly belligerent enemies in Afghanistan and Iraq, another government report noted that the armed forces “are not meeting their recruitment targets consistently [because]…an ageing population will mean a decline in numbers of individuals of working age over the long term.” However, this needs to be put in context: the report also noted that there were a host of other factors that caused or accentuated this crisis, including a buoyant economy that provided alternative careers and higher rates of obesity. In addition, less important than declining demographics is a changing population: the report noted a steady or falling birth rate in traditional areas of recruitment but rising birth rates amongst ethnic groups “which historically [have] not been attracted to a career in the Armed Services.”

THERE IS, instead, a more important reason why any state with a diminishing or even stable population is vulnerable to external aggression: Its armed forces may lack not the manpower but rather the necessary financial resources. This is not just because of a falling GDP but more specifically because it has more pressing priorities than defense expenditure. Above all, if a state’s population is ageing while its birth rates are stable or falling, thereby lowering tax revenues, then health care and social security budgets become an urgent priority that demotes other, less pressing demands.

Taiwan provides an example of how demographic decline is apt to create a demand for this type of “butter” over “guns.” Its defense expenditure fell steadily from at least 2008 until 2017, stabilizing at around 2 percent of GDP. But this prioritization was and remains closely linked to its numerical decline. The Taiwanese birth rate has not reached replacement levels since the early 1980s and today, standing at 1.17 percent, is one of the lowest in the world. In August 2016 a governmental report predicted that the island’s population will start to decrease within five to ten years.

This of course has far-reaching implications. At the moment there are 5.6 people of working age for every elderly person; by 2061 this number will have plummeted to 1.3. This means that the Taiwanese government is already spending considerable sums of money to provide health and care services for its elderly citizens while offering generous financial incentives, including tax breaks and subsidies, to young couples to have children. Defense expenditure, by contrast, is viewed by many Taiwanese politicians as an expensive luxury. Demographic decline in Taiwan, in other words, could conceivably tempt China to initiate its own Depopulation War against a state that it has claimed, since its formation in 1949, as its own territory.

This reprioritization of expenditure is also affecting countries in the Western world, including the UK and Germany, that are also confronted by a crisis of health and social care. Between 1988 and 2013, UK defense expenditure almost halved as a proportion of GDP. Welfare spending is now nearly six times higher than defense spending, whereas in the mid-1980s, health and education expenditure were at similar levels to defense spending.

Such financial pressures not only render a diminishing state more vulnerable to attack but also make it less inclined to intervene on behalf of its allies and other third parties. Although such a state is likely to maintain a capability to defend its own self, it is less able and willing to sacrifice its own resources for another country, which then becomes isolated and vulnerable to foreign aggression.

An example of this type of Depopulation War was the Arab-Jewish conflict in Mandated Palestine prior to the formation of the state of Israel in 1948. After sustaining such huge losses in World War II—which cost the lives of 382,000 servicemen—the severely over-stretched British Army was scarcely in a position to fight any further conflicts unless they were strictly “necessary.” Equally, the general British public and its government were just as hostile to any such unnecessary commitments: “Someone else should have their turn now [of] this very difficult place,” Winston Churchill observed about Palestine in 1945. Aware that the mere possibility of a British retreat would create a political and military void, both Arabs and Jews escalated their feuding against each other, as well as against the British army of occupation, in a desperate bid to fill it.

In a slightly different way, the Abyssinia Crisis of 1935 can be classified in these terms. As he calculated his chances of capturing the East African state, the Italian dictator Benito Mussolini judged that the population of Great Britain was too elderly to want to make a stand: with twelve million citizens who were aged at least fifty and therefore, in his view, “over the age limit for bellicosity,” he decided that the British nation was agreeably disposed to passivity. However, such a scenario is more likely to unfold because of a lack of human or material resources rather than because of any difference of attitude, real or imaginary, on the part of a relatively elderly population that may have little or no influence on political decisionmaking.

THERE IS also another, more indirect, connection between a falling population and strategic vulnerability. Sometimes a fall in the birth rate can be symptomatic of an affluence that may not be compatible with military values. Since 1945, for example, Germany has had a low birth rate which is thought to reflect its postwar material prosperity and high standards of living. At the same time, its armed forces have suffered from regular recruitment shortfalls: in 2012, one year after conscription ended, the Bundeswehr suffered a severe (33 percent) manpower shortage. Some analysts have called the republic a “postmilitary society” that has a disdain for the discomfort and sacrifices required by military life. This is very arguably borne of an economic prosperity that also accounts for a diminution of the birth rate.

In the years ahead, strategic realignments might prevent some Depopulation Wars from breaking out. For example, some states that are experiencing depopulation, or are at risk of doing so, will be able to strike closer defensive alliances with more affluent states, like China, India and the United States, that are in a position to guarantee their security or else provide economic subsidies that allow them to increase their own defense spending.

However, it is equally possible that serious political rifts could erupt, within and between states, should a depopulating country fail to increase its defense expenditure or refuse to strike such a deal with other states that regard its security as essential to their own.

An example is the relationship between Taipei and Washington, which is committed, under the Taiwan Relations Act of 1979, to defending the island’s sovereignty and security. In December 2016 Deputy Assistant Secretary of Defense Abraham Denmark publicly criticized President Tsai Ing-wen’s defense budget, claiming that “[it] has not kept pace with the threat developments and should be increased.” Such financial pressures may prompt allies, even long-standing ones, to question the value of such alliances and withdraw from them altogether. For example, transatlantic tensions erupted in the summer of 2018, when Secretary of Defense James Mattis suggested that the UK’s low defense expenditure is imperiling the “special relationship.”

But the threat of Depopulation Wars is also a reminder that states with a diminishing population are at least as worthy of close attention as those with increasing numbers. In one respect, they may represent a greater danger. This is because they are susceptible to the same condition as any other state, and individual, that experiences a decline and fall: the danger of defeated expectations that have been raised by the prosperity of earlier years but then dashed by the realization that it can no longer play the vigorous role of before. A demographically diminishing state may act aggressively, unleashing the “all-shaking thunder” of King Lear, in an attempt to recapture its lost grandeur: contemporary Russia is the most obvious example.

Perhaps the most important conclusion is that demographics in general merit considerably more attention. Every sort of demographic change—whether an overall increase or decline of numbers, or changes within a particular community—is apt to have wider, international repercussions, affecting the behavior either of that state or of its partners, rivals and adversaries. This means that demographics, not least the complex interplay of rising and falling populations in different parts of the world, needs to be at the very forefront of strategic attention rather than be seen as a peripheral issue.

R. T. Howard is the author, most recently, of Power and Glory: France’s Secret Wars with Britain and America 1945–2016, as well as several other books on defense and international relations.