Intelligence agencies suspect Russia is behind the mysterious “sonic attacks” against U.S. diplomatic personnel in Cuba and China, sources tell NBC News, although the evidence is not yet conclusive enough for the U.S. to formally assign blame to Moscow. The evidence includes communications intercepts picked up during the investigation by the CIA, FBI, and other U.S. intel agencies, according to the report. The incidents, which started in late 2016, have seen 26 government workers stationed in Havana report brain injuries, hearing loss, and problems with cognition, balance, vision, and hearing. A separate staffer at a diplomatic facility in Guangzhou, China, was diagnosed with similar symptoms. Many of the workers reported hearing strange sounds before developing the symptoms. U.S. intelligence officials says they believe sophisticated microwave technology, possibly in conjunction with other types of electromagnetic “neuroweapons,” was used on the targets.