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.
People's Volunteer Army
The stated historical importance of the Chinese People's Volunteer Army's entering the war was that it marked the beginning of Chinese government involvement. However, this is rather from political propaganda needs and there is debate of the time of the beginning of Chinese involvement. Some scholars in the west had argued that the Chinese involvement was much earlier, and in the North Korean invasion on June 25, 1950, out of the 135,000 North Korean invasion force, more than 38,000 were the former ethnic Korean soldiers of the Chinese Communist Fourth Field Army. An equal number of former ethnic Korean soldiers of Chinese communist IV Field Army who did not participate in the invasion also served in North Korean army in other regions of North Korea. The North Korean invasion force consisted of two corps, the 1st Corps and the 2nd Corps. Jin Xiong (金雄, Kim Woong), the commander-in-chief of the invasion force and the commander of the 1st Corps, was a veteran of Eighth Route Army, and a former member of Communist Party of China. Jin Wuting (金武亭, Kim Mu Jong), also known as Wu Ting (武亭, Mu Jong) the commander of 2nd corps, even had more seniority than Jin Xiong (金雄), in that he participated in Guangzhou Uprising and the Long March. All of these facts are agreed by the Chinese government.