South Korea: In South Korea, Auxiliary Police (AP) have a military-like structure, in that it consists of volunteers selected among eligible males (aged 18-35) who have not yet fulfilled the nation's obligatory military dutyand the service in the Auxiliary Police is accepted as an equivalent of the military duty. The length of service for the auxiliary policemen is 21 months, which is identical to that of ROK Army enlistments. Also, within the Auxiliary Police rank, there exists four sub-ranks similar to the four enlisted ranks in the ROK Army: Private Constable (이경 Yi-kyeong), Private Constable First Class ((일경 Il-kyeong), Corporal Constable (상경 Sang-kyeong), and Sergeant Constable (수경;  Soo-kyeong). When enlisted, volunteers first go through a four-week basic military training at Korea Army Training Center under administration of Ministry of National Defense. The recruits are then handed over to theMinistry of Public Administration and Security for later administration, and are given a three-week police training before being deployed to various police units (that are each no bigger than the size of acompany) throughout the country. Depending on their assignment, the Auxiliary Policemen may assist the national police with a wide array of police works, such as riot policing, traffic control, crowd control, surveillance and patrol. Upon completion of their service, Auxiliary Policemen are discharged with a Sergeant rank in the ROK Army Reserve (except in cases of demotion)