This is a perfect geo-political storm.
One can understand why NK hates Japan and the US.  Japan raped (literally) Korea during their occupation from 1910-45 and now Japan is a close ally of the US which is strangling NK economically, bombed NK to oblivion from 1950-53, and continually engages in provocative military behavior: from destabilizing the Middle-East with vicious wars to war games directed against NK.
Russia & China support NK just as they did in 1950 because NK deflects US resources away from Russian threats in Europe and Chinese aggression in Asia.  Pakistan and Iran benefit in a similar manner.  Iran is proceeding with ICBM tests (withNK) and Pakistan freely gives sanctuary to terrorists who are making sure that the Afghanistan war drags on & on.
The US naturally feels threatened by a despotic rogue regime which daily threatens to "mercilessly annihilate" the US and her allies: the RoK, Japan, and Australia.
When this storm breaks it will result in a global catastrophe.