"Kim [Il-sung] wanted his system to last, and his place in history to be assured. Since the fate of Stalin (and later of Mao) showed that he could not entrust those goals to the Party, he turned to his own family. His son, born in the Soviet Union in 1942, returned to Korea to complete his schooling and graduate from Kim Il Sung University. He rose rapidly in the Party hierarchy and was put in charge of propaganda in 1972. The Sixth Party Congress of 1980 ratified the choice of Kim's son as his successor. Kim Jong Il entered the Party Secretariat, the Central Committee, the Politburo and the Military Commission. For the first time, a Communist state was being turned into a hereditary monarchy."
January 1, 1970
https://en.wikiquote.org/wiki/Kim_Jong-il