South Korea's armed forces have declined by a fifth in six years, according to a defence ministry report, as the world's lowest birthrate reduces the number of young men available for compulsory military service.
The report, submitted to ruling party MP Choo Mi-ae, warns the army is 50,000 troops short of the level needed for defence readiness, with a particular shortage in non-commissioned officers.
Military numbers have fallen from about 690,000 in the early 2000s to roughly 450,000 now. The population of 20-year-old men, the typical enlistment age, dropped by 30% between 2019 and 2025 to 230,000.
South Korea's fertility rate was 0.75 in 2024, the lowest in the world. Its population, which peaked at 51.8 million in 2020, is projected to fall to 36.2 million by 2072.
The armed forces have shortened service periods, citing improved capabilities and the alliance with the US, as well as a growing defence industry. The defence budget is over 61tn won (£33bn).
North Korea is estimated to have an active-duty force of about 1.2 million soldiers.
