Experts examining the mysterious sonic attacks that affected dozens of U.S. diplomats in Cuba and China now believe microwave radiation may have been used to inflict brain injuries on the victims, The New York Times reports. Strikes using microwave radiation—once feared as a the next big weapon in Soviet psychological warfare and mind control—is now one of the main suspects in the 2016 phenomenon that left diplomats suffering from false sensations and with symptoms of brain trauma, according to the report. Douglas H. Smith, the lead author of a study on the diplomats affected in Cuba, told the Times that he and other scientists view microwave strikes as one of the most likely scenarios. While federal investigators have reportedly considered the microwave theory only as one of many, Beatrice A. Golomb, a medical doctor and professor at the University of California, San Diego, is due to publish a study in October making the most comprehensive case yet that microwave weapons were used in the Cuba incident. The U.S. government has not yet determined who was behind the bizarre sonic attacks, but Russia, China, and many European countries are believed to have the skills and knowledge to use basic microwave weapons.