South Korea’s military has shrunk by 20% in six years as male population drops

August 10, 2025

Seoul: A government report says South Korea’s armed forces have declined by about 20% over the past six years, shrinking to roughly 450,000 troops. The reduction is largely tied to a steep drop in the number of males of enlistment age due to the country’s record-low birthrate. The defense ministry warns the trend could lead to officer shortfalls and potential operational challenges if it continues.

The military has been shrinking since the early 2000s, when numbers stood around 690,000. The decline accelerated in recent years; by 2019, there were about 563,000 active-duty personnel and officers. North Korea is estimated to have about 1.2 million active personnel, per 2022 defence ministry estimates.

From 2019 to 2025, the number of 20-year-old males declined by about 30% to 230,000—the age most enlist, given an 18-month service term. The military attributes shorter service periods to improved capabilities, supported by the U.S. alliance and a domestically developed defense industry that is now a major arms exporter.

Historically, able-bodied men served 36 months in 1953 after the Korean War. Despite a defence budget exceeding 61 trillion won in 2025, which is larger than North Korea’s estimated economy, the force remains about 50,000 troops short of a level deemed sufficient for readiness. Approximately 21,000 of that shortfall are among non-commissioned officers.

South Korea faces rapid ageing and one of the world’s lowest fertility rates (0.75 in 2024). The population peaked at 51.8 million in 2020 and is projected to fall to 36.2 million by 2072.