China does support North Korea in many ways. However, they have recently stopped vetoing most sanctions against them in the UN because they see that North Korea has been more bellicose and unstable lately.
When I was in China recently, it was very clear on government sanctioned news that support for them is dwindling. Several college professors came on to comment calling the regime unstable and reactionary. This is new.
With that being said, however, these are not new threats from North Korea:
http://www.bbc.co.uk/news/world-asia-21710644
http://www.piie.com/blogs/nk/?p=9612
They've made threats to slash and burn the armistice agreement several times already. The only truly NEW occurrence is that they now openly state that they are producing a nuclear weapon to harm the US and it's allies. Before, everyone really knew that's what they were doing, but they never admitted it and would use the excuse that they're trying to produce nuclear power.
Most news we get about North Korea is limited at best anyways - this article is really very interesting:
http://www.theatlantic.com/magazine/arc ... /308414/1/
I think in the near future North Korea's actions are going to be largely unpredictable.