“The question is whether or not they could challenge the airspace any.”
No question about it, we own the air over SK. A lot of anti-air over NK would make it tight but their air power is minimal.
The best fighter North Korea has is the MiG 29 without an upgrade package. This fighter is obsolete even against our ANG F-16 and Paki F-16’s, and all Russian MiG-29’s currently in service with Russia and other client nations.