Foeke Postma, Bellingcat:
Like their analogue namesakes, flashcard learning apps are popular digital learning tools that show questions on one side and answers on the other. By simply searching online for terms publicly known to be associated with nuclear weapons, Bellingcat was able to discover cards used by military personnel serving at all six European military bases reported to store nuclear devices.
Experts approached by Bellingcat said that these findings represented serious breaches of security protocols and raised renewed questions about US nuclear weapons deployment in Europe.
Some flashcards uncovered during the course of this investigation had been publicly visible online as far back as 2013. Other sets detailed processes that were being learned by users until at least April 2021. It is not known whether secret phrases, protocols or other security practices have been altered since then.
It seems many flashcard websites default to public access and search engine indexing — which, while a fair growth strategy, is something users may not expect. I was able to find some of the flashcards in this article, and other presumably sensitive sets that were not. Several sets of cards could easily be traced back to individuals working on different bases because they had their full name as their user name.