Kim Il Sung sent out preliminary signals in late 1955 and early 1956, before the 3rd Congress of the Workers' Party of Korea (WPK), that he was preparing to move against the Yan'an and Soviet factions.
The 20th Congress of the Communist Party of the Soviet Union was a bombshell with Nikita Khrushchev's Secret Speech denouncing Joseph Stalin and the inauguration of de-Stalinization.
Throughout the Soviet Bloc domestic Communist parties inaugurated campaigns against personality cults, and the general secretaries who modelled themselves after Stalin were deposed throughout Eastern Europe.
Kim Il Sung was summoned to Moscow for six weeks in the summer of 1956 in order to receive a dressing down from Khrushchev, who wished to bring North Korea in line with the new orthodoxy.
In September 1956, a joint Soviet-Chinese delegation went to Pyongyang to instruct Kim Il Sung to cease any purge and reinstate the leaders of the Yan'an and Soviet factions.
[3] A second plenum of the Central Committee, held on September 23, 1956, officially pardoned the leaders of the August opposition attempt and rehabilitated them, but in 1957 the purges resumed, and, by 1958, the Yan'an faction had ceased to exist.