South Korea’s active-duty military has dropped by 20% in the last six years and now stands at about 450,000 troops. The reason behind the decline of the army is the unavailability of young men for the country’s compulsory military service, according to a defence ministry report. One of the major problems for the decline is South Korea’s low birth rate (the lowest in the world), and the shortage is making it harder to recruit soldiers and threatening operational readiness..
The report, shared with Democratic Party lawmaker Choo Mi-ae, shows that the active military had around 563,000 troops in 2019, which is down from roughly 690,000 in the early 2000s. The number of 20-year-old men, the usual age for enlistment in the army, has fallen sharply, dropping 30% between 2019 and 2025 to about 230,000.
South Korea is considered one of the fastest ageing populations in the world and has the lowest birth rate ratio (only 0.75 babies expected per woman in 2024). According to the government data, the population, which reached 51.8 million in 2020, is projected to fall to 36.2 million by 2072.
The country’s armed forces have cited better technology, strong ties with the United States (US), and a growing defence industry (major arms exporter) are the main reasons for shortening service periods. Back in 1953, when the Korean War ended in an armistice, able-bodied men served for 36 months.
The defence budget of South Korea in 2025 is over 61 trillion (£33bn), which is bigger than North Korea’s entire estimated economy. However, the armed forces in South Korea are still short by 50,000 troops, according to the report by the defence ministry.