Russia had a lot of equipment in storage, equipment that was supposed to be maintained. Strangely enough a lot of that equipment never saw any maintenance despite the maintenance budget being spent. That money 'disappeared' into someone's pockets.

Now these were conventional weapons, guns, tanks, trucks, etcetera. Stuff that you could imagine being used at some point, so there was some risk of being found out.

Now imagine you are a Russian general in charge of maintaining the nuclear stockpile. Weapons that you can reasonably expect never to be actually used. Even better, if you ever get in a situation where they would be used, it's basically the end of the world and no one is going to be alive to care if you pocketed the maintenance money anyway. How much of the allocated maintenance budget do you expect to have been spent on actual maintenance?