Trump is stepping up and forcing the issue on something that has been avoided and ignored by  administrations of both parties for years. He is confronting the Chinese for their failure to reign in their "little boy", whose been  running around randomly throwing rocks and threatening his  neighbors.  Kim is China's kid.  They 'own' him.  If anything, Trump hasn't gone far enough.  he needs to tell the Chinese that any attack coming  from N Korea on us, or any of  our allies, will be viewed as an attack from China and we will respond with a massive counter-attack on N Korea AND  China. China and N Korea  would cease to exist.
If Trump does that, China will quickly find it is in their best interest to "take away"  Kim's toys and throw him back in his play pen. They can do it and they must do it. For the peace of the world, such as it is, they have no choice.