What's to stop an adversary from broadcasting the same tone on the same frequency and overpowering the signal in certain areas? It strikes me that if the conjec

What's to stop an adversary from broadcasting the same tone on the same frequency and overpowering the signal in certain areas? It strikes me that if the conjecture (of it being a reserved frequency for war time command signals) is correct, it would be relatively easy to break. Perhaps the weekly random words are some kind of authentication mechanism, but that seems like a long time to have to wait to authenticate the signal.