North Korea, that is.
Its latest nuclear test is said to be about 20 kilotonnes, or more. That is bigger than the American bombs on Hiroshima and Nagasaki. It comes hot on the heels of what were described by the international community as "successful" ballistic missile tests over the past few weeks. Anxiety is rising over what to do.
China does not want the North to collapse, and for a couple of reasons. Firstly it does not want a unified Korean peninsula in the hands of the West on its border. It will likely do anything to prevent that, including invading the North, and that could mean war. Secondly it fears a wave of refugees of unknown allegiance.
The South (and allies) cannot invade the North, even though they are technically still at war. That would lead to Chines troops intervening in a land war, at least, between it and the West, with Russia probably aiding the Chinese.
It is all a cat and mouse game and the mouse looks to have the upper hand at the moment.