Today's Winds of Change roundup has an link which eventually leads to this report of a massing of a heavy force of Chinese PLA regulars on the North Korean border. Said force sounds like three corps of five divisions - 150,000 troops, or a light army. It's too light to be a serious invasion force, and doesn't sound like it has enough logistical tail to be on any sort of penetrative mission. Details within the report strongly suggests that it's a defensive move to cover the Chinese border from feral North Korean military units. It sounds like military discipline might be breaking down among the North Korean border forces.
There's some handwaving about the Chinese trying to pressure the North Koreans into backing down on their nuclear ambitions, but the Chinese could just cut their oil off again. That is, unless that particular threat is starting to lose its bite through over-use. In which case, the Chinese might be trying to seriously cut the oil, and putting this new army in place to guard against North Korean overreaction - such as trying to seize control of the Chinese side of the oil pipelines that the North Koreans depend on. Or maybe taking parts of Manchuria hostage in exchange for keeping the taps flowing.