Soviets back in the 70s and 80s would beam microwave and inaudible sound into our embassies to provide power for embedded bugs. Think of it as a forerunner of todays wireless cell phone charging. You didn’t want bugs transmitting all the time because then sweeps could easily pick them up.
If someone investigates what happened at the U.S. Embassy in Moscow in the 1980s, the same issues occurred at that time. The same sort of attack led to a number of diplomats being returned to the USA. It was all very hush-hush, but as I recall there was one death and the wife of a US diplomat was bought off to stop her from revealing what was happening.