“have burned up on re-entry, they don’t have adequate heat shields, yet.”
You’re really not -that- gullible are you? SK and Japan routinely attempt to recover NK missile parts to analyze NK’s technology.
The NKs don’t use heat shielding because they don’t want the warheads (and their guidance system) surviving re-entry to be collected by SK and the Japanese.
NK has only achieved 2 orbital launches that burned up oh re-entry, we have the video.
NK is not into failure, if they had adequate heat shielding they would use it. If it worked they could always signal a self-destruct on re-entry.
They would learn more that way, which is what they want.