Goyang: The military on Monday resumed an excavation project to locate the remains of four members of a former secret military unit established to train commandos to infiltrate North Korea, the defense ministry said. The military plans to excavate three sites this year where the remains of four "Silmido" unit members are presumed to be buried, according to the ministry. Earlier in the day, an event marking the resumption of the project was held at a cemetery in Goyang, just northwest of Seoul, one of the three locations where the remains may be buried.

According to Yonhap News Agency, the so-called Unit 684, also known by the name of Silmido, the Yellow Sea island where it was based, was created by the spy agency and the Air Force in 1968 after Pyongyang's failed attempt to attack the presidential office that year. A total of 24 commandos, excluding seven who died during training, were confined at the Silmido Island off the country's west coast for over three years before they staged a mutiny and escaped the unit in 1971. Of them, 20 were killed during a standoff with the military and police in southern Seoul, while four others were sentenced to death and secretly buried without their family members being notified.

The remains of 20 commandos were later discovered at the cemetery in Goyang, but the remains of the four others have yet to be found. The secret unit remained relatively unknown before the release of the 2003 film "Silmido" based on the story of its members. In 2006, the Truth and Reconciliation Commission recommended a national apology over the issue and that an excavation project be carried out to find the remaining remains.

In 2024, then Defense Minister Kim Yong-hyun issued an apology, marking the first official government apology, coming more than half a century after the members of the secret unit were killed. The government launched the excavation project the same year but failed to locate the missing remains, according to the ministry.