I first remember coming across this some years ago, but I just recently read a declassified report available from NASA about the control of compromising radiations, codenamed Tempest. This has geekery and Cold War espionage together in one place! From the report, it would seem the Russians were on to this before the Americans, which is not really surprising. Russia has a great deal of top-notch science and engineering talent. If I remember correctly, it was a Russian scientist who first theorized that you could create a material or structure that would have low visibility on radar (stealth) but no one thought anything of it, so he published it in an open access journal.
Anyhow, I first heard of this as van Eck phreaking, the surreptitious interception of CRT signals so you could see what was on someone's monitor. van Eck published in 1985, and then it turned out that the American government had known about it for years, but had done it's best not to let on.