The basic history is this: In 1910, Japan colonized Korea, treating Koreans not so much as foreigners but as a wayward subset of the Japanese race now reunited. Imperial Japan’s official worldview was race-based, far-right ultranationalism, obsessed with racial purity and superiority. It was a lot like Europe’s early-1900s fascist governments, although with a uniquely Japanese element: the quasi-religious worship of the emperor as not just the leader and embodiment of the nation but a semi-divine figure.
Koreans under Japanese rule, and especially Korean writers and officials, were recruited into this fascist worldview, which for a generation many Koreans took on and enforced as their own. Then in 1945, the Japanese Empire collapsed, and the Korean Peninsula was divided between the Soviet-occupied north and the US-occupied south. In the north, the Soviets tried to set up a friendly communist puppet government, as it was also doing in Eastern Europe. But it had a problem: There wasn’t really a leftist intelligentsia or officialdom to draw upon. So the Soviets ended up recycling in many of the Koreans who’d been a part of the Japanese fascist project in Korea.
“Almost all intellectuals who moved to Pyongyang after liberation had collaborated with the Japanese so some degree,” the historian B.R. Myers writes in his book The Cleanest Race: How North Koreans See Themselves and Why It Matters. When the Soviets set up the North Korean propaganda regime in 1946 to write the new mythology of the Korean state, Myers writes, “most of the top posts went to well-known veterans of the wartime cultural apparatus.”
The Soviets didn’t just fail in establishing a far-left communist puppet state: They ended up entrenching the very same far-right Japanese fascism the world had just defeated.
Source: The single most important fact for understanding North Korea – Vox