Its quite obvious that both China and Russia are enjoying the 'children's show' featuring the petulant man-child Trump and the equally rotund and unchecked 'fearless leader', aching for attention and respect, NK's very own Kim Jong Un.  
China wants the US to be on the ropes- courtesy of trump's abject void of knowledge on foreign policy, detente, global trade, inferred isolationism and nationalism, trump is the perfect patsy for China to become the new global leader.  
Putin disclaims trump as his wife, but still enjoys the stumbles and gaffs that trump brings to the show.  trump yaps at NK but doesn't pay attention to US intel- Ukranian technology powers those ballistic missiles!
China needs the US to be on the defensive in its truly strategic plan to promote the yuan as THE global currency, to be the leader in trans-Pacific trade, to name a few.  China also does NOT want an influx of NK refugees taking flight into China.  It will help prop up NK as long as it serves their purpose.