An even more stealth method is to make the system work perfectly if everything is running fine. Like correctly reporting net frequency in the range 49-51 Hz but reporting false values when outside of that range. That way there will be no detectable errors until everything starts behaving erratically.
The best way for a society to prepare is to have a few small incidents that put the safety systems to the test on a regular basis.
The best way for a society to prepare is to have a few small incidents that put the safety systems to the test on a regular basis.