Consumed by a siege mentality, facing sanctions imposed by the world’s major powers, a poverty-stricken nation where people were suffering from starvation and famine pressed ahead at all costs to develop its nuclear weapon programs.

Sounds like North Korea? It could also be the description of China in early 1960s.

Mao Zedong succeeded in joining the nuclear club, and no external force in the world could undermine his grip on power after that. This experience no doubt makes Beijing more aware than others that if the world does not act soon enough, Kim Jung Un can no longer be stopped.

The Kim regime apparently hasn’t been acting in concert with China’s interests. The risk of radioactive pollution on Chinese soil increases every time a more powerful bomb is detonated, due of the proximity of test sites to the Chinese border. And, despite China’s desire to present itself as a rising power to be reckoned with, North Korea undercuts Beijing’s credibility in front of the international community by refusing to cooperate with its “big brother.”

So why hasn’t Beijing taken Pyongyang’s nuclear ambition more seriously, at least not as much as its Western counterparts have? After all, although China’s central bank reportedly has started cutting off its banking business with its eastern neighbor, China still accounts for more than 85 percent of North Korea’s trade, even as President Trump warned that he’s considering “stopping all trade with any country doing business” with North Korea.

The move comes during a meeting of the United Nations General Assembly, where US officials met with Japan and South Korea, among others.

First and foremost, the fear looms large that the collapse of Kim’s regime would lead to a flood of North Korean refugees flooding across the Chinese border. Over the past several years, quite a few defectors who fled North Korea have been sent back, even though the Chinese government knew that they would face harsh punishment. There is growing reluctance among Chinese to assume obligations to settle refugees, with viral opinions on China’s social media that go something like this: We didn’t endure the one-child policy for decades to save resources for some foreign free-riders.

Also, many in China still feel the need to have North Korea as a strategic buffer zone. Ever since the Korean War era, the Chinese people have been convinced that defending Pyongyang is in essence defending the nation’s gate in the northeast from foreign aggression. Since the early 1950s, the Chinese people have been told that North Korea provided a “strategic buffer zone” between Chinese soil and South Korea and Japan, where US military were stationed. As long as the Kim family remained in power, the theory went, the US would stay away from China’s doorstep. So regime change and a reunited Korean peninsula are seen as detrimental to China’s national interest.

What has been less talked about, however, is the fact Pyongyang remains Beijing’s only ally that to some extent shares its political values. As China becomes increasingly assertive on the international stage and as ultranationalist sentiments catch fire on the domestic front, it sees “hostile forces” everywhere, from the US to Japan, from the Philippines to Singapore, from India to South Korea, while Pyongyang is among the last few standing communist regimes. As long as North Korea remains the most reclusive nation – with a horrifying record on human rights – it helps deflect the world’s attention away from China on issues like rule of law and freedom of speech. As some social media comments jokingly put it: When someone is bringing up the rear of the class, life is easier for the second worst.

This ideological kinship may partially explain why North Korea’s possession of a hydrogen bomb seems like less of a threat to China than South Korea’s US-provided missile defense system THAAD (Terminal High Altitude Area Defense). That also explains why North Korea’s evil deeds are somehow downplayed in China’s state-owned media while the government called for a boycott of South Korea-related commerce – supermarkets, cosmetics, TV productions, food, and vacation destinations – in response to the decision to deploy THAAD.

Finally, China’s once-every-five-year political reshuffle is around the corner. The last thing President Xi Jinping wants is to invite trouble in the midst of a childish yet dangerous war of words between a “dotard” and the “Rocket Man.” As it is often said by China’s ruling Communist Party, stability outweighs everything else; perhaps at this crucial moment, that “everything else” includes the difficult task of reining in a psychologically unstable neighbor.

Audrey Jiajia Li is the 2017 Elizabeth Neuffer fellow with the International Women’s Media Foundation (IWMF).