The Korean War Service Medal (KWSM, Korean: 6.25사변종군기장), also known as the Republic of Korea War Service Medal (ROKWSM), is a military award of South Korea which was first authorized in December 1950.

Originally and technically known as the 6.25 Incident Participation Medal (Presidential decree #390; 6.25 stands for June 25, 1950, the date of the beginning of the North Korean invasion into South Korea.), the colored and enameled 5-pointed star version of the Korean War Service Medal was first authorized to South Korean troops who had participated in the initial counter-assaults against North Korean aggression in June 1950.

On September 15, 1951, President Syngman Rhee referred to and authorized the commander-chief of the United Nations Command to confer the award of the "Korean War Medal" and "Korean War Ribbon" ("Korean War Service Medal"), "to the brave and valiant members of the United Nations Command who have been, and are now, combating the communist aggressor in Korea