In the Century of Nuclear Weapon, the probability of War has been declining. But i think it still remain so because the States with Atomic power still be limited.
Once the Nuclear weapon will not anymore be the privilege of the so call Nuclearpower States and the goal to reduce the nuclear Weapon Worldwide fails, then the World will not anymore be ensured.
Because of the security dilemma, if North Koreas Atomic programm be successful, the neighboring States will not be secured anymore.
To arise their security, the response of neighboring States of North Koreas atomic Programm for example South Korea and Japan will need to have the same Power (the atomic Bomb) to maintain the regional balance of power.
This may produce an domino effect and the result would be the proliferation of nuklear Weapon.
It is very urgent for the World to stop North Koreas Atomic Programm otherwise it will only be a question of time untill the human race be destroyed.
Then it is not guaranted that all the States who dispose on those Weapon and atomic Bomb, will allways be reasonable and will at the end just for the deterrence use them.