China supports North Korea financially. As I understand it, they help provide enough food to North Korea to keep the country from starving. Without support from China, it is doubtful that the North Korean regime would survive. I think it is unlikely North Korean leaders would behave very differently from how the Chinese rulers want them to behave.
North Korea has been deliberately provocative and threatening towards the United States and South Korea for many years. Their effort to develop nuclear weapons and missiles capable of delivering those weapons is only part of their provocations. They have threatened a pre-emptive first strike with nuclear weapons against the west. They have attacked South Korean territory killing civilians.
Yet, it is unlikely they would do these things without Chinese approval, perhaps even direction, because if China disapproved, they could "pull the plug" on the North Korean government simply by cutting off material support.
China needs trade with the United States. What do they have to gain by North Korean threats and provocations?
Recently there was a news item that North Korea proposed friendly talks with South Korea and that this may be a reversal of their policy of hostility in recent years. It may be that North Korea may be seeking some kind of peaceful reunification with South Korea on terms acceptable to the South Korean government and people. In effect, after years of open hostility, now they are showing a more reconciliatory face.
Link to news story:
Perhaps both the provocations and the offer to have peaceful talks are part of a long-term, well thought out plan by China.
What would be China's long-term objective? Taiwan.
The Taiwanese people and government do not want unification with China right now, and their military alliance with the United States helps protect them from being taken over by China. The United States is a strong power in that region, not only because of its own military power, but because of its close relations and military alliances with Taiwan, South Korea, and Japan. Each of those nations, though they do not have nuclear weapons, have their own considerable military strength which, when combined with American power, makes a force too great for China to directly challenge over Taiwan.
If China can detach South Korea from that alliance, it would be one step towards weakening American power in the region.
So China and North Korea could offer South Korea a deal. Break your alliance with the west and join an alliance with China, and you can have unification with North Korea on your economic and political terms. North Korea can be absorbed into the South Korean economic and political structure, much as East Germany was absorbed into the West German system when Germany united. The combined, unified Korea would be democratic and have economic free enterprise as South Korea is now, but with the added land and population of North Korea and with a military alliance with China instead of the United States. North Korean leaders would have guarantees of safety from retribution for past deeds and would have the option to live comfortably in Korea or China. South Korean companies would continue their trade with the west, and the population of all Korea would enjoy the same personal freedoms that South Koreans have now.
The policies of North Korea, the past provocations and the recent proposal for talks, may be the carrot and the stick. First they threaten war, then they offer a way out.
If the United States, through its own weakness, allows such a policy to succeed, and if the unified Korea does well in its alliance with China, that may give Taiwan and Japan food for thought. They have to consider, as the United States bankrupts itself with debt and as China grows economically, if the United States will have the political will and the resources to maintain a strong enough military presence in the region to be a reliable ally against China in the years to come. In effect, South Korea will have answered that question with a "no" if they choose China as an ally over the United States. Japan and Taiwan would have to think about that.
Moreover, a unified Korea would combine the military forces of both Koreas, with North Korea's nuclear weaponry and South Korea's economy and technical proficiency. Such a combined military, allied with China not the United States, would effect a real change in the balance of power in the region.
Then, if China proves itself friendly to the new Korea, scrupulously keeping its side of the deal to the letter, and Korea remains free and prosperous, China would have a positive track record it could show in negotiating a unification deal with Taiwan.
All of this could help fulfill prophecy about Europe.
If the United States permits this to happen, and if the Europeans view this as a sign of America's weakness and decline, that will help them realize that the days of the United States being a strong and reliable ally may be numbered. This would motivate them to develop their own military forces to a greater extent and work harder to unite to protect themselves. If they think they can no longer rely on the United States to defend them, they will have to become stronger to defend themselves.