JIM MIDDLETON, PRESENTER: North Korea's highly provocative threats against the United States and South Korea have raised tension and fear around Asia-Pacific.
All the way, China has called for restraint.
But behind the scenes is an unusual debate about whether the time has come for China to re-evaluate the friendship with its temperamental neighbour.
China correspondent Huey Fern Tay reports.
(Footage of North Korean military rally plays)
HUEY FERN TAY, REPORTER: Threats from North Korea have always been dramatic in both form and substance. Events over the past two weeks have seen an escalation of intimidation, from a declaration of a state of war with South Korea to an announcement that the Yong Byong nuclear facility would be restarted.
The US has reacted with alarm announcing plans to move its missile defence system to a base in Guam.
South Koreans, who are used to this rhetoric from their next door neighbour, felt the need to also remind the North it wasn't complacent.
WI YONG-SUP, SOUTH KOREA'S DEFENCE MINISTRY SPOKESMAN (translation): We consider a North missile launch is always a possibility and we've got our measures ready for it. We are ready to respond if the north launches a missile.
HUEY FERN TAY: China, Pyongyang's only friend, has called for restraint. This is in line with its previous actions.
In his speech at the Gao forum over the weekend, Chinese president Xi Jinping cautioned that peace was crucial to the future development of the region.
But he also made comments that were seen as a warning for North Korea.
XI JINPING, CHINESE PRESIDENT (translation): The international community should advocate the vision of comprehensive security and cooperative security so as to turn the global village into a big stage for common development rather than an arena where gladiators fight each other. And no one should be allowed to throw the region or even the whole world into chaos for selfish gains.
(Footage of Korean War plays)
HUEY FERN TAY: The alliance between China and North Korea during the Korean War is often referred to as the turning point of the relationship. But behind the scenes there's been a growing debate about whether Beijing should reconsider the friendship.
Today at Beijing supports the North with much needed fuel arms and fuel.
But after Pyongyang conducted its third nuclear test in the middle of China's most important holiday, the Spring Festival, some prominent Chinese commentators began saying enough was enough.
The unusual debate has caught the attention of Kim Heung kyu who is a former adviser to South Korea's presidential council.
KIM HEUNG-KYU, SUNGSHIN WOMEN's UNIVERSITY (translation): North Korea is kind of a liability. North Korea is like a, island isolated, and also providing China's no more the benefits but some obstacles to extend the Chinese economic activities over the east and north east Asia.
HUEY FERN TAY: It is difficult to gauge whether Chinese policy makers feel the country need to change the way it deals with its unpredictable neighbour. Also difficult to assess is the amount of public support for this argument.
Professor Wang Dong, from Peking University, says the loud voices of approval could become a factor behind any change if their magnitude grows.
PROFESSOR WANG DONG, PEKING UNIVERSITY: So I would urge, I think, observers to really look closely at that phenomena. Because if the public, the ordinary people sentiment towards North Korea changes, that means a lot. I think that would it's a significant change because that will in the long term, in the long run, provide a basis for even top leaders to re think their policy towards North Korea.
HUEY FERN TAY: A deviation from China's longstanding policy on North Korea, if any, is a long way away. Still, that hasn't stopped people from asking China to break away from the norm by stemming in to do something.
North Korea has become a card in China's strategic considerations, and analysts say that's an overriding concern.
WANG DONG: Even though they feel it is impossible for them to change their policies because of the structure, you know, they build. So there is the ongoing rivalry between the United States and China, and also the still low level of political trust between China and South Korea and also the existence of the US Army on the Korean Peninsula. And also the most important one is the hidden agenda, you know, Taiwan Strait issues, unification of China.
HUEY FERN TAY: As the birthday of North Korea's founder Kim Il sung approaches, the question is whether his grandson, Kim Jong un, will do more things to get attention.
It's one of many unknowns about this country, which is how it prefers to operate. But the uncertainty is a worrying factor for many others.