In Western and South Korean media coverage the February 12 murder at Kuala Lumpur airport of Kim Jong-nam, half brother of North Korea's supreme leader Kim Jong-un, was immediately interpreted  as an indicator of serious and growing tensions between China and estranged ally North Korea.
The broad, if unverifiable assumption at present is that Pyongyang ordered the hit on on the regime sibling, who lived with his two families in Beijing and Macau under China’s protection, in order to eliminate a potential pretender to the throne. If this version is true, it would be a major embarrassment for Beijing, whose relations with its communist neighbour are souring by the day.
Thus far, most Chinese state-affiliated media outlets have withheld from commentary on the news, reflecting, perhaps, a certain paralysis in China over how to react to the shock development. Certainly, after China's criticisms of North Korean nuclear policy, the two countries are no longer “close like lips and teeth”, as Modern China's founder Mao Tse-Tung once said.
Nevertheless, Chinese nationalist commentators who tend to see U.S hegemony as a major source of threat to the country — and North Korea as a traditional ally — filled the void of silence with speculation that pointed a finger at South Korea instead.
They accuse Seoul of carrying out the assassination in order to gain public support for deploying  the controversial Terminal High Altitude Area Defense (THAAD) missile defence system that the United States supports, and which has ratcheted up tensions with the north.
Few users of the Chinese Twitter equivalent Weibo seemed to buy that theory, however.
The nationalist-leaning Global Times first quoted the online conspiracy theory  in its news report dated February 17:
There is an online conspiracy that the [government] in South Korea may have been involved in the incident as they are hostile towards North Korea. They may have killed Kim Jong-nam and blamed North Korea for the act, so that international society would condemn Pyongyang.
The paper then quoted Lu Chao, a researcher at the Liaoning social science academy to provide backing for the conspiracy theory:
South Korean politicians and media are overjoyed with the news about Kim Jong-nam’s death. These media outlets keep publishing “breaking news” [on the topic]. The effect of the incident is like LSD. South Korea sees the news as a “powerful bomb” to defame and subvert North Korea. From this point of view, it is no longer a piece of news but part of a political plot.
Seemingly, commentators such as Lu Chao view the THAAD system as a greater threat to Chinese national security than North Korea's nuclear tests, despite increasing evidence that China has as much reason to fear Kim Jong-un's unpredictable regime as other countries in the region.
On Twitter, prominent Chinese journalist Gao Yu condemned those still backing North Korea:
金正男马来西亚遇刺，是震惊世界的恶性恐怖事件，刚刚听到VOA对中国两位学者的采访，他们认为这件事对中朝关系影响不大，金正恩大权在握，政权巩固，反而说这为刚刚上台的美国总统川普制造难题。中国产生这样泯灭人性的学者只能令人齿寒，也让世人看清杀（姑）父弑兄的金三胖有恃无恐搞核恐假谁威！ pic.twitter.com/ADbzPK98nJ 
— 高瑜 (@gaoyu200812) February 15, 2017 
The assassination of Kim Jong-nam in Malaysia is a terrorist incident. But I just heard two scholars talking to VOA who argued that the incident would not affect North Korea’s relationship with China because the fact Kim Jong-un remains in power creates difficulties for U.S President Trump. Such cold-blooded scholars are terrifying. Their view tells the whole world who is supporting Kim Jong-un, the maniac who killed his uncle and his brother.
On the Weibo comment thread under a China Central Television news report on the topic, most commenters stated their belief that North Korea was the most likely culprit in the assassination.
The whole world know that the incident is a protest against China by Fatty the Third (Kim Jong-un). The fatty launched missiles and expected Chinese backing for his actions […] But this time, China condemned North Korea and claimed that it would stop giving support to North Korea (and banned North Korea coal import ). Relations broke down. Fatty was worried that China would support the reformist Jong-nam to take over the leadership… and Jong-nam was killed.
Only the stupid ones believe that North Korea is China’s little brother […] China cannot exercise any political influence over North Korea, but it has to offer supplies to the country.
My gut feeling is that China will help the reunification of North and South Korea. As to THAAD being a threat to Chinese national security… that is very far fetched. Only when the two are reunified will northeastern China and [the region] know peace. But China has to help out… if the U.S takes the lead in reunification, it might be another story.
Unlike certain nationalist armchair pundits, meanwhile, residents of the northeastern region of China fear North Korea far more than they fear THAAD and South Korea: 
I don’t want to say too much. All I know is that because of Kim Jong-un’s nuclear tests, we have experienced a few earthquakes here. The most serious earthquake happened last year, when kids in school had to run to the sports fields and the school headmaster decided to cancel the school day because of security concerns. Those who cheer for [Kim Jong-un], please think about the safety in Northeastern China. And don’t forget you are Chinese.