Predict a Korean War of Reunification scenario

[Frodo]

During one of those missile tests that North Korea likes to conduct, one strays off course and hits Anchorage -a freak accident.  Trump being Trump, he immediately declares war, despite Kim Jong-un's panicked apologies, and launches air strikes that effectively destroy North Korea's nuclear capability.  He subsequently orders a build-up of American forces in Northeast Asia in preparation for an invasion.  China -by this time distracted by an economic collapse, urban and rural discontent, and facing nearly simultaneous separatist uprisings in Xinjiang, Tibet, and Hong Kong- accedes to Trump's demands to stand aloof, on condition that South Korean and American forces do not cross the Yalu.  

After a few months of sometimes heavy fighting, North Korea is under allied control and occupation, and the Kim regime is destroyed.    

[Frodo]

If we're going for unrealistic, perhaps Kim Jong Un attacks to the north to repatriate Yanbian from Chinese control.

It's 'Mad Dog' Trump we're dealing with now -not 'No Drama' Obama.  I can see him reacting disproportionately to any provocation, real or imagined.  Any miscalculation on the part of the Kim regime will spell its doom.