George Friedman discusses what war with North Korea might look like. Note that he puts emphasis on having good intelligence. See below an assessment of US intelligence.
Former NSA counterintelligence office believes that for US intelligence, North Korea is a black hole. He also points out that N. Korea has not been shy about attacking US military and S. Korea assets.
Commentary from a serving officer personally known to me who is on the ground in Korea:
"Interesting articles. Not sure I agree with the tactics of a preemptive strike. Things could have changed since back when DPRK sank the Chonin in the West Sea. ROK was more than a little upset about that one.
"Two years ago there was a substantial artillery duel across the DMZ. Much directed at the US training area for the exercise. DPRK took the worst of it, by a long shot.
"The north has a vast number of tubes. No telling what their maintenance status is on any given day, or ammo stocks. I think their capabilities are routinely overestimated to stir up fear and loathing.
"The terrain here is no joke. There's no mounted maneuver outside the 4 main north-south mobility corridors. That means cannons don't move south without detection and interdiction.
"The US keeps a large Multiple launch Rocket System unit and a huge attack helicopter brigade here for a reason. It's a nice package for suppressing enemy air defense in support of helicopter deep attack. Those RF Hellfires are simply a thing of wonder. When not doing SEAD, the MLRS do a great job in their counter-battery role. Good gear to have around.
"We can't keep Seoul completely safe from DPRK artillery. We can shut it down relatively quickly, even in bad weather that limits fixed wing assets.
"I am not worried about DPRK cannons and I live inside their long range systems range fan.
"I won't comment on intel other than to say it's not the black hole it's advertised to be. It's not as easy as Iraq where we had lots of sources, but we are far from blind.
"Could Trump stumble into a war here? Sure. Anything is possible. He would have to try pretty hard to do it tho.
"The best way to deal with all this is to call Kim's bluff. Something like a UN Security Council resolution that terminates authority for United Nations Command and establishing the DMZ as the new border. Concurrently the US and ROK offer a one page peace treaty declaring end of hostilities. The mechanics of this are a little tedious but it can be done unilaterally.
"No more frozen conflict, and no more excuses for provocation. Future aggression can be dealt with as a new tort without the distortion of past battles.
"If DPRK declines those terms, then it's clear they have evil intent. Then a case can be made for protecting civilized states.