Fred99:

 

... they wanted help from Russia or the US  to "launch a weather satellite" and spat the dummy when told no. I wonder about that - what the problem would have been, ...

 

If you can launch an object into a Polar orbit, you can make it come down anywhere in the world. It would probably have limited payload though. OTOH, if you can launch an orbital vehicle, then you can also launch a sub-orbital vehicle which could come down anywhere in half the world, but with a much larger payload.

The USA and Japan don't want North Korea to have this capability. Depending on your point of view, that would be either a pistol at USA's head, or bring balance to North Korea's bargaining position by negating the USA's nuclear threat.