The memorial will be built at an existing ⁠cemetery for North Korean ​“martyrs” in the northern province of Bac Ninh outside Hanoi, the report said. The downed pilots were part of a group of around 100 that North Korea dispatched to North Vietnam to train their Vietnamese counterparts in the mid-1960s. The airmen were among the estimated 1,000 North Koreans who were secretly sent to North Vietnam between 1966 and 1971. For years, the role of the North Korean army in the Vietnam War was veiled in secrecy. The decision to actively support North Vietnam was made in 1965, and endorsed by a meeting of the ruling Workers Party the following year.