If one analyze US actions in pacific region and specific to NK, US actually painted itself in the corner and so did two of its subservient states Japan and South Korea.
If US had not used its typical instrument of "sanction", threats and ratchet up tension, there would been much better situation than NK missile hitting Japan and South and potentially even US. THAAD or whatever US has, provides no guarantee of defense, specially swarming salvo of missiles. South Korea and Japan can solve problem with north or at least keep situation at the level where no one threat any one. But neither Japan nor Korea act for their own interest rather working as tool for US hegemonic policy.
Even yesterday, China proposed to mediate and clam the situation with proposal to halt US & South Korea naval drill in exchange for preventing NK from lobbing missiles. But both South Korea and US rejected the Chinese mediation proposal.
So what can one make of US, South Korean and Japanese intention? US is gearing towards a war in pacific and they intend to drag China. If South Koreans and japan can not see their own self destruction, who can help them? No one.
Another big elephant Russia, which recently deployed improved missiles and missile defense in Pacific coast and even in Kuril Island chain, had not spoken on NK issue in last few weeks. But Russia made it clear that it will work with China to defeat THAAD.
US is busy opening as many contentious fronts as possible. Testing to see how many of these fronts China and Russia can counter simultaneously.