My concern is that if China allies with the US to stem the  insanity of NK's nukes and ICBMs, Putin and Russia will step in to help NK.  Xi knows he is better off being friends with Trump than with Kim.  China does not want millions of North Korean refugees flooding across the border in case of war. Putin doesn't give a damn about either China or the US. For that matter, Iran could come to Nk's aid too.