Of course he does not have a plan. Neither did Obama. They are not military men, they rely on advisors.
It is has come to the point that diplomacy is a total waste of time, as are sanctions. You can't negotiate or reason with the leaders of North Korea.
They do not feel remorse or pity.
Trump does not have a plan, but he can make things happen after he gets sensible advice.
Obama could have also.
The Chinese leadership is weak, only cares about staying in power, and China does not have the military strength to take on North Korea by itself.
The Americans have the superior technology and strategies.