It's widely acknowledged and understood that Russia is deploying some kind of acoustic weapon: the damage among multiple Cuban embassy staff has been quantified and described in medical journals.

All these recent attacks on the CIA and other government officials by Russians in Russia and elsewhere in Europe have just confirmed that they were behind the Cuba attacks, and some originally suspected.

Edit: Looking into the research, there are dissenting voices who believe that explanations other than a weapon are possible. But the authors of the two studies I saw published leaned toward some type of offensive weapon. After WMD debacle, I should be more careful with my conclusions.