Chinese died in Korea to prevent the takeover of a fellow socialist state by American imperialism.
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It is pretty hard to justify anyone dying to defend Kim Il Sung in Korea. First off, North Korea invaded South Korea. They did this because the understood that the US would not retaliate, based on statements from the US government that should never have been made.
Second, Kim Il Sung and Kim Jong Il have to be among the least competent rulers on the planet of any ideology. They make Mugabe look good: at least Zimbabweans can flee his incompetence.
The PRC soldiers may have been told that they were defending a workers' state, but the reality is that China did not want any capitalist state on its border. They had to put up with Hong Kong and Macau, but they were not going to put up with a capitalist Korea, which was a threat from both a military and a political view.
South Korea was a wreck in 1950, after the Japanese occupation, as was the North, but by 1990 it had passed out of the "developing world" status" and now it is clearly first world. In North Korea, they are still eating grass and weeds, if they are not starving. The North Korean Army could overthrow Kim, but the officers know that they would lose their prestige and could only hope for driving cabs in Seoul at best. It will take North Korea around 30 years at least to approximate the development standards of the South. East Germany was already pretty well developed, but North Korea sucks at every level.
I don't see any way anyone can defend North Korea as a society or as a country, compared to what it could be after unification.