Dang gum you guys! I TOLD you that I did not even go in the Army until June of '70! GEEZ!! Get your decades rights!
The "Cone of Silence" was first used in the 1950's. I was just a kid then. We did not need such arcane devices. We had black cloths. It was well known at the time that the Soviet counter intelligence officers were unable to move, or even approach, ANYTHING that was covered by a black, polyester, cloth. We used them extensively at the time. Black polyester cloths was the "Kryptonite" of the Soviet.