The full cost of replacing North Korea's fighters

Why not modernise North Korea's fighter fleet with new aircraft?

Replacement requires available production capacity and money for aircraft, pilot training, maintenance and logistics, with delivery delays limiting its immediate usefulness.

Replacing the MiG-29s starts with finding a production line that can supply another aircraft. Russian and Chinese lines are described as occupied with their own requirements. Changing type would require a new training profile, maintenance arrangements and logistical support. The aircraft purchase is only part of that expense, since pilots must be trained and the supporting system reset. A replacement arriving many years later would offer little help with the immediate capability problem.