Why South Korea’s Military Has Shrunk by 20% in Six Years?

The military of South Korea has shrunk by 20% over the past six years, falling to 450,000 troops. The main reason is due to a steep drop in the number of young men eligible for mandatory service, according to a defence ministry report released on Sunday. 

South Korea has reportedly the world’s lowest birth rate, and this is creating a growing manpower shortage.

The report was presented to Democratic Party lawmaker Choo Mi-ae. It was made public by her office, which warned that the decline in recruits is also leading to a shortage of officers. If the trend continues, the military could reportedly face operational challenges.

According to reports, South Korea’s military strength has steadily fallen since the early 2000s, when it had around 690,000 soldiers. By 2019, that figure was down to about 563,000, and the pace of decline has since accelerated. According to 2022 data from the defence ministry, North Korea is estimated to have about 1.2 million active-duty troops.

Between 2019 and 2025, the number of 20-year-old men in South Korea dropped by 30% to just 230,000 — the age when most enlist after passing a physical exam.

Currently, mandatory service lasts 18 months. The military says this is possible due to improved capabilities, its alliance with the United States, and a strong defence industry that is now a major arms exporter.

South Korea’s 2025 defence budget is set at over 61 trillion won ($43.9 billion), larger than North Korea’s entire economy.

However, the army is still short of 50,000 troops needed for full readiness, with 21,000 of them in non-commissioned officer positions.

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