Bahk Eun-ji has been with The Korea Times since 2012, building a career across multiple desks. She began at the Business Desk, where she conducted in-depth interviews with key figures in Korea's corporate world. Later, she moved to the Politics & City Desk, focusing on education policy and social affairs. She later served as team leader of the digital content team, leading curation efforts on the newspaper’s homepage and reshaping print stories for social media audiences to enhance digital reach. Now back on the Politics Desk, she covers the National Assembly and the Ministry of National Defense, with a renewed focus on political developments.
Korea's military faces deepening troop shortage due to plummeting birthrate
President Lee Jae Myung shakes hands with soldiers during his visit to the Army’s 7th Division in Hwacheon, Gangwon Province, Sept. 12. Courtesy of presidential office
By Bahk Eun-ji
Concerns are mounting that a sharp demographic decline could weaken South Korea’s ability to deter threats from North Korea, with the South’s military projected to shrink to roughly 270,000 troops by 2040.
According to data provided by the Ministry of National Defense to Rep. Yu Yong-weon of the National Assembly’s defense committee project, Korea’s active-duty military personnel is expected to decrease to 290,000 in 2030, 260,000 in 2035 and 150,000 by 2040. Including officers, the total force is expected to fall to about 270,000 by 2040, down from approximately 450,000 this year.
In contrast, North Korea is expected to maintain about 1.13 million troops through its universal conscription system, which obliges men to serve for 10 years and women for seven. Current estimates put the North’s force at around 1.2 million. With little sign of change in Pyongyang’s policy, the gap between the two militaries is set to widen further.
The imbalance would leave South Korea below the “minimum planning ratio” set out in U.S. military doctrine, which states that a defending force must be at least one-third as strong as the attacking force to stand a realistic chance of success. Based on current projections, South Korea's military would be only one quarter the size of North Korea's by 2040, falling short of that threshold.
A study by the state-run Korea Institute for Defense Analyses concluded that South Korea would need to maintain an active-duty military of at least 500,000 troops to repel a North Korean attack. While Seoul enjoys technological and training advantages, researchers said that sheer numbers still matter. They warned that the armed forces could struggle to maintain a force of even 300,000 troops by 2040 if the country's birthrate continues to fall.
The report urged the government to consider steps such as extending service terms or combining conscription with voluntary enlistment. It also cautioned that advanced weapons could not fully compensate for shrinking troop numbers.
These concerns have been echoed by other experts.
The KAIST Future Strategy Research Institute has recommended widening recruitment pools and considering female conscription, as well as investing in technologies such as quantum-enabled surveillance systems, in order to ease pressure on manpower.
“The decline in military resources poses a direct threat to national security and demands prompt, coordinated responses at a national level,” said Cho Sang-geun, a KAIST professor.
President Lee Jae Myung weighed in on Sunday, promising sweeping reforms to build what he called “a smart, elite military force” armed with advanced technology. In a Facebook post, he pointed to artificial intelligence-powered combat robots, autonomous drones and precision-guided missiles as tools that could allow smaller units to take on much larger enemy formations.
Lee said that, while South Korea's standing army is smaller than North Korea's, the country has 2.6 million trained reservists ready for mobilization, as well as a defense budget and economic base that far exceed those of Pyongyang. “We must not measure our defense strength by head count alone,” he wrote.
He also stressed the need to lessen reliance on foreign forces, rejecting what he described as a “submissive mindset” that questions South Korea’s ability to defend itself. The president pledged to strengthen the defense industry, increase military spending and expand multilateral security partnerships to ensure the country is never left vulnerable to external pressure.
The debate underscores the scale of South Korea’s demographic crisis. With the pool of 20-year-old men eligible for conscription expected to shrink to about 140,000 by 2040, the military faces stark choices in sustaining its strength in the years ahead.
The government’s ambitious push to modernize its forces and move toward greater self-reliance could offer a strategic path forward, but it collides with a demographic reality that is emerging as the nation’s most formidable long-term challenge. As policymakers plan for advanced weaponry and international alliances, their most urgent task may be simply figuring out how to maintain a standing military.