If you can achieve orbit, you can hit any point on earth. A “minimum energy trajectory” connecting any two points on earth always uses less energy than an orbital trajectory.
So they need more work to get it in orbit. I just thought, psychologically speaking, nuke(s) orbiting around the Earth, hovering overhead, ready to come down and vaporize you would be more terrifying to general public than some missile launched from a location inside N. Korea.
If you can achieve orbit, you will stay in orbit, finally falling to Earth eventually..