The German Ministry of Defence had a patent classified as a state secret — on the grounds that it could compromise NATO's nuclear deterrence. However, because AI was used in the creation process, secrecy could no longer be guaranteed. The patent was declassified. The inventor has since decided to publish the full research publicly.
Tagesschau report (German):
https://www.tagesschau.de/investigativ/wdr/patent-staatsgehe...