It's no secret that the only reason North Korea managed to survive so long after the fall of the Soviet Union is because of China's patronage. There are a number of possible reasons it's in China's best interest to prop up the Hermit Kingdom. Long story short: China will intervene for North Korea just as it did in 1950.
The DPRK is a buffer zone between Communist China and the pro-Western ally in South Korea. More than that, the sudden fall of the Kim regime would essentially open the 880-mile border between the two to roving parties of North Korean refugees, suddenly freed, looking for a future.
The Yalu River is the natural and political border between the two countries.
The highest estimates indicate some 30 million internally-displaced persons – refugees in their own country – would suddenly be looking for a better life. Beyond the human toll, the cost of the reunification of the Korean Peninsula could be as high as $3 trillion, as one expert told the Independent.
China is certainly not going to share that cost. Nor will it take in refugees. The people of China are not fans of North Korea either. They resent the North Korean nuclear tests and the effect it has on China's foreign policy – and its relationship with the United States.
North Koreans celebrate their relationship with China at the annual Arirang Mass Games.
Chinese people take to Quora to answer the same question over and over, "How do Chinese people feel about North Korea?" Time and tie again, the answer is that they are "sympathetic" to the people of the DPRK (though sometimes they use the word "pity") because the country reminds them of when China was underdeveloped. In general, however, they mock Kim Jong-Un "mercilessly."
The North Korean leader is believed to be losing trust in his relationship with the Chinese, and acts out in an effort to embarrass Beijing. In return, there is less trust in China for the leadership in Pyongyang. But as for the United States, the Chinese have less trust in President Trump.
Despite all this, the 1961 Sino-North Korean Mutual Aid and Cooperation Friendship Treaty is still in effect, and is renewed automatically every 20 years. Article 2 of the treaty states that the two nations will jointly oppose any country or coalition that might attack either nation. The treaty is valid until 2021. But it also stipulates that both sides are to "safeguard peace and security."
Some former Chinese military officers believe North Korea's nuclear proliferation is a violation of that treaty and China is no longer on the hook to defend the Kim Regime. Many Chinese intellectuals believe the North Korean state is no longer their partner in arms, but more of a liability.
"Many in China don't want North Korea to have nuclear weapons because nuclear weapons are, first, threatening to China," Chinese scholar Shen Zhihua – an expert on the Korean War – told the New Yorker. "We must see clearly that China and North Korea are no longer brothers-in-arms, and in the short term there's no possibility of an improvement in Chinese-North Korean relations."
But the state's view remains the same. Just after the Kim regime threatened to attack the U.S. island of Guam, the Global Times, a state-run newspaper said China will "firmly resist any side which wants to change the status quo of the areas where China's interests are concerned."
Essentially, the Communist Party mouthpiece is saying that China will intervene if the United States escalates the conflict to a shooting war. However, if North Korea starts the war, China will remain neutral.
"The Korean Peninsula is where the strategic interests of all sides converge, and no side should try to be the absolute dominator of the region."