Wow — a paid shill for North Korea or an ill-informed fool.
The Korean War is still technically going on (despite 64 years of general peace) because it only ended in an armistice. That is the case because North Korea was then (1953), and has remained since, unwilling to accept a complete peace that leaves South Korea separate. While the US has considerable force in South Korea they are certainly NOT “poised to invade at moment’s notice” — US and South Korean aren’t situated for attack and they are far too few to invade unless suicide is their goal. The mention of Japan as a threat is somewhat specious since they’ve been pacifistic for 72 years and have nowhere near the power to threaten North Korea.
So, are they crazy? Many would think so since they’ve chosen to build and sustain their military strength even though it’s kept them a pariah and has come at the expense of food for their people. If large percentages of your people starve with regularity because you’re focused on dubious threats and you viciously stamp out any descent, you’re likely crazy.
As for agreements … it has become the norm for North Korea to ‘rattle its sabers’ (fire missiles, do nuke development, reach agreements with countries like Iran, etc.) every few years. It does this because the typical Western response has been to ‘cave’ and basically give North Korea some grain, money, etc. It’s kind of like some vikings did at some periods of time — showing every decade or so demanding money or they’ll loot, burn, and kill.