Kim Jong-un was forced to start the rhetoric by his own army, to maintain his seat of power. With at least one or two reported coups defeated over the past couple of years, Kim Jong-un needed to not only distract his military but move them away from political power bases. Frankly, putting the army on war readiness (keeping them busy) and away from the capital is probably the best thing Jong-un has done.
That said, Jong-un is suffering from a complete lack of experience and a god-complex that diminishes his fear of making a mistake. He may not want war, but he may end up with it anyway if some rogue general decides that the best way to de-throne Jong-un is to restart the Korean conflict.