which foreign power has been operating them since the
Middle Ages?
Klaatu barrada nikto.
There are two more, reasonable, possibilities. The first is an, as yet, unidentified natural phenomenon. That’s unlikely but certainly possible.
The second and, to me, most likely is the efforts of another cryptic alphabet soup agency, more secret that the NSA and beholden to virtually no one. Our government is no longer accountable nor bound by any limits, legal or otherwise.