South Korea’s military has shrunk by nearly 20% over the past six years, largely due to a dramatic decline in the number of men eligible for mandatory military service, according to a new report by the country’s defence ministry.

The report highlights the growing impact of South Korea’s plunging birthrate the lowest in the world on national defense readiness. The sharp fall in the pool of eligible male recruits is not only affecting the size of the military but also contributing to a shortage of officers, raising concerns about the armed forces’ long-term operational capacity.

According to the ministry, the number of active-duty troops has dropped from approximately 599,000 in 2019 to around 480,000 in 2025. The trend is expected to continue unless sweeping policy or structural changes are implemented.

“The shrinking enlistment pool is now beginning to affect our ability to maintain force structure and readiness,” the report stated. “We anticipate growing challenges in filling officer and non-commissioned officer roles over the next decade.”

South Korea mandates military service for nearly all able-bodied men, usually for 18 to 21 months, due to the continued threat from North Korea. However, with fertility rates falling to a record low of 0.72 births per woman in 2024, manpower shortages are becoming a strategic issue.

The government is reportedly considering reforms, including a possible reduction in service length, expansion of voluntary professional forces, and greater reliance on technology, such as AI and unmanned systems, to offset manpower losses.

Conclusion:

Analysts warn that unless demographic trends reverse or defense policies adapt quickly, South Korea could face a critical imbalance between national security needs and available military personnel especially in the context of ongoing tensions on the Korean Peninsula.