The Republic of Korea Army (ROK Army, ROKA, Korean: 대한민국 육군, Hanja: 大韓民國 陸軍, Revised Romanization: Daehanminguk Yuk-gun) is the largest of the military branches of the South Korean armed forces with 520,000 members as of 2011. This size is maintained through conscription; South Korean men must complete 21 months of military service between the age of 18 and 35. The Republic of Korea maintains a well equipped army, making it one of the most powerful in Asia. Its primary function is to defend the country's terrain from enemies, most notably the DPRK.

The army is structured to operate in both the mountainous terrain native to the Korean Peninsula (70% mountainous) and in North Korea with its 1 million strong Korean People's Army, 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.

Korean Army may refer to:

South Korea ( listen), officially the Republic of Korea (Hangul: 대한민국; Hanja: 大韓民國; Daehan Minguk  listen), is a sovereign state in the southern part of the Korean Peninsula. The name "Korea" is derived from Goryeo, a dynasty which ruled in the Middle Ages (an initial "G" in Korean is pronounced like an English "K").

Its neighbors are China to the west, Japan to the east, North Korea to the north, and the Korea Strait to the south. South Korea lies in the north temperate zone with a predominantly mountainous terrain. It covers a total area of 99,392 square kilometers and has a population of almost 50 million. The capital and largest city is Seoul, with a population of 9,794,304.

Archaeological findings show that the Korean Peninsula was occupied by the Lower Paleolithic period.Korean history begins with the founding of Gojoseon in 2333 BC by the legendary Dan-gun. Following the unification of the Three Kingdoms of Korea under Silla 668 AD, Korea went through the Goryeo Dynasty and Joseon Dynasty as one nation until the end of the Korean Empire in 1910, when it was annexed by Japan. After liberation and occupation by Soviet and U.S. forces at the end of World War II, the nation was divided into North and South Korea. The latter was established in 1948 as a democracy, though political turmoil and times of military rule and martial law characterized much of the period until the foundation of the Sixth Republic in 1987.

The Korean War (Korean: 한국전쟁 or 조선전쟁, Hanja: 韓國戰爭 or 朝鮮戰爭; 25 June 1950 – 27 July 1953) was a war between the Republic of Korea (supported primarily by the United States of America, with contributions from allied nations under the aegis of the United Nations) and the Democratic People's Republic of Korea (supported by the People's Republic of China, with military and material aid from the Union of Soviet Socialist Republics). The Korean War was primarily the result of the political division of Korea by an agreement of the victorious Allies at the conclusion of the Pacific War at the end of World War II. The Korean Peninsula was ruled by the Empire of Japan from 1910 until the end of World War II. Following the surrender of the Empire of Japan in September 1945, American administrators divided the peninsula along the 38th parallel, with U.S. military forces occupying the southern half and Soviet military forces occupying the northern half.