Kim Jong Un. AP/David Guttenfelder Chinese media has published a run of negative articles over its supposed ally, North Korea, the BBC reports.

The articles have appeared in China's Beijing News, the Global Times, and the personal blog of a prominent political commentator.

The presence of these articles in China's tightly controlled media could signal growing frustrations within Beijing over North Korea's continuous confrontational stance with the rest of the world.

In the Beijing News, an article warns that people should remain suspicious of North Korea and its "flip-flop attitude."

The article goes on to say, according to a translation from the BBC, that:

because of the lack of integrity, its [North Korea's] verbal statements are not going to convince any country … It tried to gain attention by planning the top official's visit to Seoul, however, this is meaningless as the most important question is whether Pyongyang will give up its nuclear programme.

A second article in the Global Times, a state-run tabloid, features an interview with Jin Qiangyi, an international affairs expert at Yanbian University. Qiangyi said that China is unlikely to offer meaningful support to North Korea because of the ongoing nuclear standoff. This diplomatic chill is pushing Pyongyang to reach out to with countries such as Russia, Japan, and South Korea.

A high-ranking mission from North Korea, possibly the "most senior" such delegation ever sent from the north, visited South Korea for impromptu talks at the end of the Asian Games, which were held in South Korea. This charm offensive could be a reaction to China's increasingly unfavorable view of its Korean ally.

Qiu Lin, a prominent political commentator, pointed out that "North Korea's leader Kim Jong Un has not visited China since coming to power. This shows that his heart is not with Beijing ... as they are unhappy with Beijing's warning over its nuclear programme."

North Korea and China are still allies, even if their relationship has grown frostier in recent years. China is North Korea's primary trade partner — but tensions between the two countries have been growing since Kim Jong Un took power in 2011, with China likely deciding that a close alliance with a belligerent pariah state just isn't worth the trouble anymore.

North Korea's responded in kind. In April, the regime allegedly released a memo encouraging officials to "abandon the Chinese dream." The memo went on to criticize China for its closeness with "imperialists" because of North Korea's belief that Beijing has sided with the US against their nuclear program.

In August, North Korea reportedly moved its most advanced tank unit towards the Chinese border. The mobilization came after China was believed to have conducted military exercises along its side of the border in April.