Did the US ever even claim to find any evidence of the Havana syndrome being caused by energy weapons? Like, they closely investigated for over the decade while it was apparently going on. The technology to detect EM waves from long wave radio all the way up to gamma rays has existed for a long time and isn't anything novel at this point as far as I know. And while there are ways of making signals hard to detect, they pretty much all require the received energy to be somewhat similar to the backgrouond noise level and preferably quite a lot lower. Instead, a directed energy weapon would have be irradiating the receiver with quite a bit of power unless the Cuban/Soviet forces found some special signal that can disrupt brain activity. And even then, if it follows a specific pattern, then the odds of detecting it would go up a hell of a lot.