It was likely similar to the warhead storage bunkers in Czech Republic (or Czechoslovaki back then), most likely intended for tactical nuclear weapons, like Scuds or maybe for aircraft as well:

https://www.expats.cz/czech-news/article/top-secret-cold-war...

https://www.rferl.org/a/24993733.html

https://www.euronews.com/2021/07/18/czech-cold-war-depot-for...

Of course the Soviets (who were exclusively running and guarding those bunkers back then) never confirmed what they were used to or if they contained live nuclear weapons. But it is clear that this was the intended use case, given the storage conditions, the expens to build & run those as well as how heavily they were guarded.