How can USA President Trump prepare for war with North Korea in the next 6-months?

No one wants war with North Korea, however if backed into a corner and North Korea attacks the USA or one of our allies, then the USA must be prepared to act and respond militarily. 
Yes I am afraid, just like people were afraid when US President Kennedy had to deal with the Cuban Missile crisis in October of 1962. 
If North Korea attacks America or one of our allies are we supposed to just try to negotiate verbally with Kim Jong-un? 
Hell NO.  
Then it would be time to destroy the leader of North Korea and save the North Korean people from starvation.