Nuclear War with NK

OP drastically overestimates NK's power.

They would never be able to nuke anyone except perhaps SK. Even if they had the missiles to hit the US (they don't), even if the US and allies hadn't already destroyed the launch sites or missiles themselves or surrounding infrastructure (they would, probably all of the above), even if they successfully fired them (pretty hit and miss with current tests), then you've still got the potential anti-missile systems, which the US keeps pretty secret and are probably more advanced than we realise, particularly regarding electronic warfare.

China would not be stupid enough to get involved. They have too much to lose. But then, neither would the US in the first place, most likely. Both sides will continue to pose at each other until the NK regime collapses, probably in a couple of decades via internal assassination.

And so will NK with the US missiles

I think we all hope China wouldn't get involved, but recent militaristic posturing by China doesn't particularly support the theory that they are going to remain a rational player - they have been extremely bellicose over the Senkakku and have had been playing dangerous near miss games with Japan and the US. If anything, Trump's recent love-in with their government aside, I would say China is currently in a hostile posture towards the US and Japan far more than it has been at any time since Mao.

When you add to that Trump's new rhetoric, which the US hasn't previously engaged in, I would suggest we are heading towards a much more serious situation. It might not be now, but it might be soon. Pre-emptive strikes on NK missle and nuclear development sites may appear unavoidable to Washington. They may fail to win Chinese support for that (my guess is that in that situation, China will react in an anti-US and pro-DPRK way) and then the way is set for NK retaliation which will be aimed at SK and potentially Japan. (If they can get some missiles to work in reality and not just for pretend - a big if, admittedly.)

The real crunch will come when NK starts firing artillery barrages at Seoul - what then? What would SK and the US do? The answer seems inevitable - a full series of major strikes against NK military forces. At that point, my guess is, the Chinese military will come to the fore in the endless power struggles in Beijing and will go for all out war against the US.

I genuinely think we are in a much more dangerous position than previously and this is not just a rerun of the usual posturing nonsense from NK.

Well, the Korean War never actually ended of course, particularly from the NK government viewpoint. They've been trying to kick it off again for some time.

My scenario was different to the original conflict, I envisaged NK seeking to draw Japan in and then China and Japan engaging - this isn't by any means an unlikely situation, there have been ongoing hostilities between China and Japan in recent years over the disputed islands which China laughably claims belong to it. Kim's people believe this will work too, which is why they keep lobbing missiles in the direction of Japan.

Seoul is WAY out of range of artillery so it's not even like Seoul could be shelled.

No its not. There are lots of modern artillery pieces that can fire the 50km or so needed.

Otherwise largely agree. Except it won't even get that far.

You think the North has "smart" munitions and reliable rocket assisted shells? I was referring specifically to unassisted artillery.