First, as many of you know I am a Republican, but not a Trump supporter........saying that, this whole N. Korea issue is not any fault of President Trump, this has been building since George Bush Sr. presidency if not before, unfortunately it could very well come to fruition under President Trump's watch.
The biggest threat from N. Korea is not their Nuclear weapons, but their Chemical and Biological weapons, they are thought to have huge stockpiles and as crazy as that guy is, the will to use them. At this point it still does not appear that they have the capability to weaponize a Nuclear weapon, but if they don;t , they are very close and will have multiple weapons in a few years, one estimate is around 90 warheads , ballistic missile capable by 2019.
It should get interesting in the next 30 days or so, the US is deploying THAAD to S. Korea and the first batteries should be operational by mid April, the North Korean's have said that they will take the systems out before they become operational, and the most troubling aspect is that China and Russia seem to be backing the North Korean's on that. Once THAAD is operational, the N. Korean Ballistic Missile threat will be seriously down graded.
One big factor, that a lot of people may not realize is that the Korean war is not officially over, no treaty was ever signed, only a cease fire , and the North Korean's will not consider it over until they have unified the entire country under their control