It would be an additional cost, but it might make sense to require that military contractors include full documentation of production methods with their products. There could be odd measures like keeping the records sealed for a time to protect secrets, but it seems like anything the nation needs to defend its interests should not be left in the hands of the producers who are expected to abandon it.
That concept works well enough for something simple and mechanical like an assault rifle, but it totally falls apart for aerospace products. Just because you have documentation doesn't mean you are actually capable of building the final product. In the real world, manufacturing engineers often make adjustments on the fly to get stuff working. And the designs often assume a particular set of tools, so without knowing how to recreate those tools you don't have anything useful.
