The entry, still available on the Federation of American Scientists' website, reads:
Nonlethal weapon which includes (1) a neuro-electromagnetic device which uses microwave transmission of sound into the skull of persons or animals by way of pulse-modulated microwave radiation; and (2) a silent sound device which can transmit sound into the skull of person or animals. NOTE: The sound modulation may be voice or audio subliminal messages. One application of V2K is use as an electronic scarecrow to frighten birds in the vicinity of airports.
The U.K.-based group Christians Against Mental Slavery first noted the change (they also have a permanent screenshot of the page). A representative of the group tells me they contacted the Webmaster, who would only tell them the entry was "permanently removed."