I have a hard time believing it's just an attempt to cook brains. What's the point of that? Plus, if it's a demo, the point has been made. Unless the perpetrator is waiting for U.S. intelligence to write up a top-secret report of the effects, which they will then pilfer and read at their leisure.
If I was going really dark to look for an explanation, I would say the Chinese (who are crushing Russia in tech advances) are testing out some mind reading equipment.
It really is a mystery.