Conscription in South Korea
By law, when a Korean man turns 18 years old, he is enlisted for "first citizen service," meaning he is liable for military duty, but is not yet required to serve. When he turns 19 years old (or, in some instances, 20 years old), he is required to undergo a physical exam to determine whether he is suitable for military service. The table below shows the physical exam's possible grades and their outcomes, according to the Military Service Act. Men must enlist by the time they turn 28 (Korean age).
The length of compulsory military service in South Korea varies based on military branch. Active duty soldiers serve 21 months in the Army or Marine Corps, 23 months in the Navy, and 24 months in the Air Force. After conscripts finish their military service, they are automatically placed on the reserve roster and are obligated to attend a few days of annual military training for 6 years.
Republic of Korea Army
The South Korean army is structured to operate in both the mountainous terrain native to the Korean Peninsula (70% mountainous) and in North Korea with its 950,000 strong Korean People's Army Ground Force, two-thirds of which is permanently garrisoned in the frontline near the DMZ. The current administration has initiated a program over the next two decades to design a purely domestic means of self-defense, whereby South Korea would be able to fully counter a North Korean attack.