However, once troops are massed, they can be used for different purposes, too. Such as locking down Pyongyang and purge any possible obstacle to Kim Junior's succession in one massive sweep.
I have a hard time believing those 2 NORK combat divisions are there for a military parade. I would imagine the NORKs have special parade units for that.
Moving combat divisions off the line (particualry for resource poor NK) and to the capital sounds like Kim wants a little muscle closer to home just in case things with his son’s transition to power don’t go smoothly or, on the other side of the spectrum, perhaps even a coup in the works.