The answer would be to overthrow the North Korean dictator but in his case, he's a lunatic who would use his nuclear bombs on the allies fighting to liberate North Korea and reunite it with South Korea. If he goes, that's the end of North Korea. But declaring war on North Korea would bring a nuclear Holocaust so it's very dangerous. They didn't have nuclear bombs during the Korean War and North Korea wasn't the cult that it is now. Back then it was no different than other Communist countries and it would be like overthrowing the dictator in places like the Soviet Union, China, or Vietnam who have whole armies behind them. But the North Korean dictator is the head of a personality cult.