What President Trump should do are as simple as his election promise, he should Stick to his pre-election plans, i.e. to allow both Japan and South Korea to have Nuclear Weapons, the two nations can curb North Korea.
The post WW2 agreement on Japan is no longer binding at a time China and North Korea were not in the picture as Nuclear nations.
United States of America must normalise relationship with Russia, it is unfortunate the Democrats created a mess for Trump’s administration at a time Russia is needed on both China and North Korea
Lastly, US must face China the real enemy of America in business opportunities.