Undiscovered bullshit. A wideband electromagnetic (or acoustical) detector is trivial to construct, especially if the levels are high enough to cause physical damage.

Undiscovered physics that somehow only Leninist states have their hands on? Which, in this case, would have to be discovered before the Sino-Soviet split of 1956, but not by anyone else?

Isn't it obvious? adjusts tinfoil cap The ruskies have figured out a way to attack anyone who has breathed in our freedom air. They pumped their censored/locked air with specific anti-freedom(terror loving) characters which causes immediate discomfort to our free minds. Freedom.