A couple of years ago there was a report that the UK had 'lost' the ability to refurbish their trident sub-launched nukes, due to losing all details of key components used in their manufacture. So supposedly, they are all in varying degrees of viability, getting worse over time as the components degrade and cant be replaced.

I wonder if that was russian espionage, messing with a state likely to be an enemy in the near future to degrade their capabilities.