Apparently china wants to maintain the status quo on korea penninsula.
To China, N.korea is a strategic buffer and its existence is an leverage and strategic assets to negotiate with the U.S.  Anyway, China will not let N.Korea collapse or become a united front with the US army stationed near china's door.  THis is what china worries the most.  If China lost the strategic buffer on korea penninsula, china lost its strategic leverage in asia.

So based on this analysis, china's response can be surmised

DO you agree?
What do  you think?