209th Detachment, 2325th Group (), commonly known as Unit 684 (684부대), was a black operations unit of the Republic of Korea Air Force formed to assassinate North Korean leader Kim Il-sung in 1968, in retaliation for the Blue House raid. The unit consisted of 31 civilian recruits, mostly petty criminals and unemployed youths, and underwent three years of harsh training on the island of Silmido. The assassination mission was cancelled in 1971 and the unit mutinied, resulting in a gun battle in Seoul in which most of the members of the unit were killed. The four survivors were sentenced to death by a military tribunal and executed. Formation The 209th Detachment, 2325th Group was founded on 1 April 1968 by the Korean Central Intelligence Agency (KCIA), the main intelligence agency of South Korea, on the orders of President Park Chung-hee. According to the Ministry of National Defence the unit, nicknamed Unit 684 after its founding date, was officially a detachment of the Republic of Korea Air Force’s 2325th Group, which recruited 31 civilians, either petty criminals or unemployed youths who were promised money and jobs if they succeeded in their mission. Unit 684 was formed to retaliate for the Blue House raid, a failed attempt by North Korea's Unit 124 to assassinate Park, which had occurred two months earlier in late January. Unit 124 was a black operations unit of the North Korean Special Operation Force created specifically to assassinate Park in an operation to enter secretly across the Demilitarized Zone and kill him at the Blue House in Seoul to trigger political turmoil. However, Unit 124 were detected by the police only 100 metres from the Blue House wearing Republic of Korea Army uniforms, and 29 of 31 commandos were killed within a week. Park decided to mirror Unit 124's mission by forming an elite black operations unit of 31 men to assassinate Kim Il-sung, the leader of North Korea. Unit 684's members were trained on Silmido, a small uninhabited island off the coast of Incheon in the Yellow Sea. Members of Unit 684 endured three years of exceptionally harsh training, during which seven members died. Mutiny Unit 684's assassination mission was cancelled in August 1971 following an improvement in relations between North Korea and South Korea. On 23 August 1971, the 24 surviving members of Unit 684 mutinied, killed all but six of their guards, and made their