....Just developing one does not ensure the ability to deliver it.
The first Hydrogen weapons that were developed weighed tons. Aircraft were devised to solely carry them (B-58 Hustler was one). It took decades of well funded research and a lot of dedicated, educated, well paid (and well fed) Scientists to develop fieldable weapons.
I think that the Norks would have a hard time delivering a fission weapon to the target due to size and weight problems. A hydrogen weapon is 10 times worse.