Korean nationalism has not only energized the North’s march to nuclear armament, but also exerted a growing appeal on people in the South — the ideol… - Brian Reynolds Myers

Nationalism is about putting the (ethno-)nation above liberal-democratic and leftist values alike. Once one takes that step, one is not separated from other nationalists by anything irreducible.

The DPRK derives its legitimacy from the myth that the anti-Japanese hero Kim Il Sung was all right-thinking citizens' choice as the man to found and lead the new Korea after liberation in 1945... Until the mid-1960s the USSR was credited with defeating Japan, but since then propaganda has claimed that Kim and his guerillas freed the race on their own. That this is known to be untrue by those who lived through the time is of minor importance. The painful historical reality of mass collaboration (and the military insignificance of all armed Korean resistance to colonial rule) is precisely what made the Kim myth so attractive.

[I]n a confederation the South must accept the ultra-nationalist Kim Il Sung cult, whereas the North must acknowledge only the South’s superior prosperity and technology — and one of the main goals of confederation is to eliminate that gap as rapidly as possible. (It will be as much a matter of pulling the South down as the North up.)