There are two major branches for Reserve Forces: the Mobilization Reserve Forces (Korean: 동원예비군, Hanja: 動員豫備軍) and the Homeland Reserve Forces (Korean: 향토예비군, hanja: 鄕土豫備軍). Soldiers who completed their service in Republic of Korea Armed Forces are automatically transferred to Reserve Forces and must serve first 4 years as Mobilization Reserve and then next 4 years as Homeland Reserve. During the wartime, about 5 divisions will be formed under Mobilization Reserves, and deployed to war zone to provide support and regional stabilization. In the meantime, Homeland Reserve will defend the mainland from any possible attacks from the enemy.
The Homeland Reserve Force was established in April 1968 as part of a nationwide program to increase emergency defense capabilities against sudden North Korean aggression. In January 1968, a North Korean commando unit infiltrated Seoul and attacked the Cheong Wa Dae in an attempt to assassinate President Park Chung Hee. That same month, two additional North Korean commando units launched attacks on towns on the Korean east coast in attempts to encourage the South Korean populace to overthrow the government.
In 1980 there were over 90,000 civil defense personnel in the country. By 1990 there were more than 3.5 million civil defense personnel in reserve. Their missions included air raid defense, search and rescue missions, building and road repair.