The way the UN has been in regards to use of force lately, I don't know if they would sanction a war with NK even if they started it, The Reason in My Opinion = China and possibly Russia, China and in some regards Russia, would feel compelled to back and support NK even if NK started a war.
NK has a whole new dimension to the concept of war with them... US must tread carefully on this one. NK has designs on SK without a doubt, I would also think they have somewhat design On Japan due in part to WW2, But that would embroil the US and our allies, China could also use this as a pretext against Taiwan if a war should start with them & NK against us. Quite intertwined in that part of the world.
just some ideas Mac