<P> It is administered by the Military Manpower Administration . There are two tiers of service : active duty or non-active duty service . Length of service varies according to branches : 21 months for Army and Marine Corps , 23 months for Navy , 24 months for Air Force . The non-active duty service , e.g. civil service or public service worker , is from 24 months to 36 months . 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 . </P>
how long do south korean males have to serve in the military
21 months for Army and Marine Corps 23 months for Navy 24 months for Air Force