You might be right.  China went into Vietnam ...why?  Oil perhaps?  Seems odd, but that is what some of our vets say.
China benefits from NKorea making trouble...not on this level, but China gets their minerals, etc.  NKorea keeps us engaged while they exploit their needs for weapons from China.  China and Iran has given these morons the nukes.  They haven't "invented" anything there.  It is weapons for materials in trade.  
Here is how this could play out. Trump just said if they say one thing more, they will be toast.  I believe him.  Canada is there now, they carry our water, and are telling this idiot to cool it or else.  There is a full moon tonight.  In two weeks we will likely be lighting that place up when the moon goes black.  Trump has 3 carriers there.  He is ramping up to this, and will take out every sub that NK has.  Pyongyang is toast.  The Palace is toast.  There are no good options unless China does this little fat man in.  Prediction:  Fat man will invite disaster.