No ide how it is in the US military, but the military supply chains I know face the risk of having obsolete parts, parts not being compatible with certain aircr

No ide how it is in the US military, but the military supply chains I know face the risk of having obsolete parts, parts not being compatible with certain aircraft configurations, reused parts, used and damaged spare parts... And, in case of civilian hardware (e.g. AWACS engines, Poseidon aircraft...) also counterfeits.