Security-Demography Dynamics in Japan, South Korea and China

By Adrien Benito

Published on Feb 26, 2025

Last October, the USA and South Korea deepened their defense technology partnership, focusing on quantum technologies, artificial intelligence and autonomous systems. Innovations and their deployments are becoming increasingly important in countries' defense architectures, particularly in East Asia. What is the connect between such developments and the evident demographic shifts in these countries?

Northeast Asia is one of the most affected regions by demographic shifts. For decades, Japan, China and South Korea have faced low birth rates. In 2022, it was respectively 1.2, 1.3 and 0.8 children per woman. At the same time, the population is ageing. In 2023, the proportion of the population aged 65 or over in Japan exceeded 30%. The same year it was 14.3 for China and 18.4 for South Korea. Now, one aspect of the demographic reversal in East Asia is the beginning of population decline. After Japan, it is now China and South Korea's turn to start shrinking.

Shrinking Population and Defence Capability

Overall, the demographic crisis increases their dependency ratio (% passive population aged 65+ years old or under 15 years old compared to active population between 15 and 65 years old). This situation, exacerbated, is not the ideal age structure to create economic growth and generate revenue for the states to support military expenditures. This deepens social tensions in the society and weakens the country's unity. A demographic crisis is a source of instability and uncertainty for the economy and for the structural organization of society, and in so doing, undermines a country's security architecture. The shrinking demography also weakens the real physical capacity to mobilize people, for example in South Korea, where the army system runs on conscription, the number of the military fell below 500,000 in 2022 and is slated to decrease further at 396,000 by 2038. All these negative consequences can be very risky for East Asian countries, given the tense geopolitical landscape of the Indo-Pacific region. This demographic shift could alter the balance of power in the region.

Paradigm Shift

Faced with these risks, one of the main strategies for dealing with demographic challenges is to adapt the country to new ways of waging war, and perhaps even to reinvent it. From this perspective, demographic change is not seen as a problem, but as a fact.

The most important solution according to the states is the development of new technologies to replace human labor in the military sector (and in the economy and society as a whole). With new technologies, the nature of warfare is changing, and so is the way war is conducted. By relying more on technology, the defense sector is seeking to compensate for the decline in the number of soldiers. This strategy requires huge investment in research and development, which in turn increases the defense and military budgets. This is being witnessed in East Asia, an increase of the defense budget and simultaneously a decrease of the military personnel. For the period 2010-2020, South Korea increased its defense spending by 43.13% and decreased its military personnel by 8.55%. In China, the gap is even wider, as they increased their defence budget by 89.34% and decreased their human resources by 10.94%.  In comparison, Japan within this period was the most stable with an increase of 3.75% in its defense spending and a decrease of 0.24% in its personnel. But in 2022, Prime Minister Fumio Kishida, sensing shifts in regional power balance and Russia's invasion of Ukraine, announced the goal of doubling the defense budget to 2% of GDP by 2027.

Then, an ageing population or even a shrinking population does not mean a weaker state. There is no linear link between a growing population (or large population) and military force (or efficiency). The most important part is the productivity and the efficiency of the army, and this is largely its capacity to have and to use new technologies in conflicts. The demographic crisis in East Asia is therefore not the only reason for increased spending on new technologies, given their centrality in today's conflicts, but it is one of the factors weighing in the balance as it exacerbates this need.

Limits of Technological Solutions

The changing nature of warfare thanks to new technologies also brings with it new problems. These new threats are often referred to as part of a hybrid warfare strategy. This is characterized by foreign interference in a country with the aim of destabilizing it from the inside, using strategies of manipulation and disinformation. It is in this context that new tools including artificial intelligence and quantum technologies are used for cyber operations.

The second limitation of the technological approach is that it cannot replace all humans. Even with the growing role of drones and robotics in the field, conflict zones still need people to fight physically, as is evident in war zones like Ukraine. This is particularly true in certain critical areas of the military, where human experience and reasoning are crucial to achieving the best adaptability, behavior and agility in a given war zone. Additionally, whether in the field or not, to develop new technologies and put them to use, a growing number of specialists will be needed.

 The demographic situation of countries always has a major impact on national security issues. However, ageing societies and demographic decline seems to be a less important variable in the future, given the changing nature of conflict and greater dependence on technology. One thing to keep in mind while talking about the relationship between demographics and security in East Asia is that the current demographic crisis has many different effects in addition to the direct repercussions on security issues. These effects, like the economic situation for example, can themselves directly affect national deterrence capacity. So, demography has both direct and indirect impacts which makes it important to put into perspective and link with other factors to measure its impact.

Adrien Benito is currently a Research Intern at the Kalinga Institute of Indo-Pacific Studies (KIIPS), India. He is also pursuing his Masters in Asian Studies at Geneva University, Geneva.

Disclaimer: The Views in the Article are those of the Author

Pic Courtsey: Australian Army Research Centre