We've known North Korea had prototype nukes lying around for several years. We, meaning the US in particular, chose to focus elsewhere.
Now we, meaning Australia as well for some utterly inexplicable reason, choose to prod and poke this insane little nation with condemnation and sanctions.
Why is this pointless? Because...
We are just bluffing and they know it;
They could care less about economic sanctions- this is an old style dictatorship happy to starve its citizenry in the process of preserving power;
We would not and pretty much could not mount a conventional war on North Korea, they have one of the most powerful militaries in the world and are incredibly close to South Korea, and not that far away from Japan;
Our only military option would be to strike North Korea right now with several nuclear devices, which won't happen; and
They may be lunatics but, unprovoked, there is no evidence that they would seriously consider rekindling the war with South Korea or attacking anyone else.
The US is calling a non-existant bluff. North Korea hasn't actually demanded much, they want the US to meet with them directly, primarily because it feeds the ego of their delusional leader. So what? If this all ends in tears, and hundreds of thousands of dead people, do the people who fucked up Iraq really think historians will look back and say 'they were right to refuse to meet and talk'?
Argue all you want. I'm right. This is a fast track to nothing gained and everything, EVERYTHING to lose....