Impending Nuclear War On America By North Korea. What?

I must have been living under a rock for a while. Nuclear war? Haven't we learnt anything?
Sometimes I think those in leadership positions have been taking stale drugs.

What exactly have we learnt from WW1, WW2, the Iraq war etc? I'm not an expert on politics but WTH?

 This is how the New York Times reported it.
 "This week, North Korea’s young leader, Kim Jung-un, ordered his underlings to prepare for a missile attack on the United States. He appeared at a command center in front of a wall map with the bold, unlikely title, ‘Plans to Attack the Mainland U.S.’ Earlier in the month, his generals boasted of developing a ‘Korean-style’ nuclear warhead that could be fitted atop a long-range missile".

 Mr Kim’s open talk of a new Korean war came after his regime threatened America with a “pre-emptive” nuclear strike. The belligerence came in response to the unanimous vote in the UN Security Council on Thursday to impose further economic sanctions. These measures followed North Korea’s third test of a nuclear bomb last month.

 Despite all the posturing, experts believe that North Korea is highly unlikely to start a war. South Korea benefits from a US security guarantee, meaning that Mr Kim would almost certainly lose any conflict. North Korea has a small nuclear arsenal, but it does not yet have an operational missile capable of striking the US.