Is this the particular attack reported by Google last month that the NSA warning was about?
https://cloud.google.com/blog/topics/threat-intelligence/rus...
[edit: yes, it is. https://www.scribd.com/document/843124910/NSA-full]
Presumably the NSA warning required ability to read above the third grade level.
Everyone is focusing on the securiy angle, but to me the most egregious thing about having these conversations over Signal is the use of disappearing messages. Perhaps these conversations/minutes would need to be classified, but they should absolutely be recorded.