Still conventional A-bomb, not a Hydrogen bomb as they claim.
You don’t know that. That is in the range of fusion weapons. Thats the yield range where most of our H bombs are.
By design, not because we have no choice in the matter. The Technology difference between A-bomb and H-bomb is quite substantial. It took the best scientists in the world another seven years to figure out how to make a successful Fusion bomb with all the resources of the United States.
If the Norks have done it, it can only be because someone gave them the design and possibly some components as well.