A Cuban government investigator looking into reports of mysterious acoustic attacks on US and Canadian diplomats on the communist-run island on Monday dismissed a US government theory that microwave weapons emitting concentrated beams of radiation may have been used in the incidents. “If you look at the alleged events, there have been reports that there are several people in a room with thick walls and thick windows and only one person was targeted. This is a kind of weapon that doesn’t exist,” said Dr. Mitchell Valdes-Sosa, a well-known neurologist who is part of the Cuban special task force investigating the alleged attacks. “It’s science fiction, not science,” he said. “First, it was sonic weapons, now microwave. What’s next, kryptonite?” the investigator said in an interview with CNN at his research center in Havana, referring to an earlier theory that sonic weapons emitting high-powered ultrasound waves could have caused the injuries. Valdes-Sosa said researchers and investigators are working on a paper to rebut the microwave weapons theory. Previously, the government not only denied involvement in the attacks but cast doubt on whether they actually occurred. In June, Cuba’s Foreign Ministry said “political motivations” drove the United States to withdraw its embassy personnel. Though a March report based on the examinations of 21 diplomats who served in Cuba didn’t link the attacks to microwaves, the study’s lead author, Douglas Smith, director of the University of Pennsylvania’s Center for Brain Injury and Repair, told The New York Times that US diplomats in Cuba and China likely suffered brain injuries and that microwaves are considered the culprit. Valdes-Sosa said for a microwave weapon to work it would have to been used at a close distance, and none of the diplomats reported seeing the alleged perpetrators. He said that Cuban authorities had investigated the report that one diplomat who suffered an apparent attack had seen a van speed off and that the vehicle belonged to a church. While the US has not directly blamed the Cuban government for carrying out the attacks, US officials said Cuba is responsible for safeguarding the diplomats well-being and that Cuban officials would likely know if a third government were responsible. But Valdes-Sosa said after more than a year of US, Canadian and Cuban investigations there was still no hard proof that any attacks actually took place. “For an attack to have occurred you have to have a real victim. First the thing we are not sure is if all these people evacuated from Cuba are really ill or have suffered do something that happened to them,” Valdes-Sosa said. “Second, you have to have a perpetrator. Who would be interested? You have to have the opportunity.” In a Sunday interview with CNN, Smith said microwaves are “a main suspect” in causing the diplomats’ injuries, but ultrasound and infrasound were being studied as potential causes as well. “It’s almost like a concussion, but without a concussion – meaning that they look like individuals who have persistent concussion symptoms but have no history of head impact,” Smith said, describing the injuries and explaining that learning the cause is vital to determining the best means of preventing it. “Just like we have ways to prevent people from having a concussion, you could think of maybe protecting your brain from these energy sources,” he said. What we know about the attacks Most of the attacks came in 2016 and 2017, though there have been a handful of reported incidents this year as well. A senior administration official told CNN that investigators have torn apart buildings where diplomatic employees encountered the sounds but found no acoustic devices, leading law enforcement to believe that the injuries were the result of microwaves beamed from a nearby location and that the “sounds” were merely a means of masking the microwave attacks. This is only a theory, the official said, and there is no concrete evidence to back it. However, brain scans on the injured personnel showed changes that indicate damage, the official said. In a statement, the US State Department on Sunday neither confirmed nor denied the possibility that microwaves were behind the diplomatic injuries. “The health and well-being of our personnel remains our top priority,” the statement said. “The investigation into the origin of these symptoms continues. The inter-agency community is working diligently to determine the cause of the symptoms, as well as to develop mitigation strategies.” Secretary of State Mike Pompeo said earlier this year he was establishing a Health Incidents Response Task Force, led by Deputy Secretary of State John Sullivan and including representatives from the departments of Justice as well as Health and Human Services. The task force will serve as the “coordinating body for department and interagency activities, including identification and treatment of affected personnel and family members, investigation and risk mitigation, messaging, and diplomatic outreach,” Pompeo said in a statement. The sophistication of the attack has led US officials to suspect a third country is involved, perhaps as retribution against the United States or Canada – whose diplomats have also been targeted – or to drive a wedge between those countries and Cuba. In August 2017, officials included Russia among a list of countries that have an adversarial relationship with the United States and that American investigators suspected might be involved.