> 18 months into a war that Russia's government had otherwise been preparing domestically for
Eh, I think we all saw how "prepared" Russia was.
In any case, I think the following factors are definitive here:
- No one really considers the current situation as "permanent". The war will be over at some point and life will go on. So investing in manufacturing of those specific parts might prove a waste.
- This is specifically an issue with parts for foreign aircrafts. Is it even worth producing parts for foreign crafts?
- There are ways to evade sanctions and smuggle parts and right now, to some degree
- Russia passed a legislation allowing 3rd-party parts and signed a contract with Iran on airplane maintainance and parts supply - Iran already has an expertise and industrial capacity operating in somewhat similar conditions. Iran also has more experience smuggling.
Obviously, that work had started many months ago, not just now.