Valid concern, no doubt, a possibility that cannot be fully ignored. However I think (my opinion) even China and Russia would not give NK the ability to start WW III or, more importantly, the ability to strike at them if NK got mad enough. These sats spend as much time over China and Russia as they do over the US. An EMP over the US may badly hurt some of our home based responses, but would not hurt in the least our distributed response capability. Such a device may reduce the US counter strike capability, but would not eliminate it, it may stagger the US, particularly the citizenry, but would not eliminate the US military or intelligence apparatus. You can't hide these sats, or any sat really, so the platform would never be in question, and you cannot hide the signature of the weapon used so the source of the device would be revealed. Such an attack, by itself, could not quickly topple the US so unless someone is willing to follow up such an event with other, more direct, strikes, all it does is scream "hit me in the face, please". So I don't see a lot to gain by either China or Russia providing such a device to NK.
Sure, provide them some raw material, provide them some tech support, all that does is allow them to, eventually, build the weapons themselves with a verifiable technology and effort backtrail. I think that is what we see in the historical record, no unexplanable tech jumps from externally delivered / developed items, and that record just does not support such a device being available to NK in time for those launches.
Today might be a different story, today NK may be able to orbit such a device, maybe. But probably not in 2016, and almost certainly not in 2012.
Just my opinion.
T!