Though not normally a Trump defender, I'm not sure I agree with your bold statement:
"can a country be only “partially destroyed?” Of course not."
There are degrees of destruction, I believe.  Fortunately Mexico City was only partially destroyed in the recent earthquake, while  sadly Hiroshima was almost totally destroyed by our bomb.  While urban Germany was largely destroyed in WWII, what Mr. Trump is threatening North Korea with  is total destruction.  We easily have the nuclear power to do that.  However in the meantime North Korea will have largely destroyed urban South Korea.   
("it might seem shameful to raise a lighter side")