In August 2017, reports began surfacing that American and Canadian diplomatic personnel in Cuba had endured unusual health-related incidents, dating back to late 2016. Twenty-two employees of the State Department reported experiencing what were referred to as "health attacks".
The State Department determined that the health problems were either the result of an attack or exposure to an as-yet-unknown device, and did not believe the Cuban government is responsible. Affected individuals described mild brain damage similar to a concussion and symptoms such as temporary or permanent hearing loss, memory loss, and nausea. Speculation centers around a sonic weapon, with some researchers suggesting similarities to Wind turbine syndrome and pointing to infrasound as a possible cause. Charles Liberman, a hearing loss researcher at Harvard Medical School and Massachusetts Eye and Ear in Boston said, "There is a growing controversy about people who live near these windmills who start feeling bad, They get headaches, they get dizzy, they get nausea [sic]". However, the scientific consensus is that the use of a sonic weapon is implausible. Dr. Timothy Leighton has said "If you're talking about a ray-gun rifle knocking out someone with ultrasound they can't hear at a hundred meters—that's not going to happen".
The United States expelled two Cuban diplomats in response to the illnesses. In September, the US State Department stated that it was removing non-emergency staff from the US embassy, and warned US citizens not to travel to Cuba. In October 2017, the Associated Press released what it claimed was a recording of the sound some embassy workers heard while in Cuba. Senior neurologists consulted by The Guardian suggested that the health incidents were probably psychosomatic complaints, of the kind commonly known as mass psychogenic illness. However, US embassy individuals have experienced lasting health effects, including one US diplomat who now uses a hearing aid.
In December 2017, investigators discovered brain abnormalities in the victims. The white matter of the brains showed changes, which doctors believe could not be caused by sound, although the sounds reported could be a byproduct of the damage.
The Cuban government offered to cooperate with the US in an investigation of the incidents. It employed about 2000 scientists and law enforcement officers interviewing 300 neighbors of diplomats, examining two hotels and medically examining non-diplomats. NBC reported that Cuban officials stated that they "also analyzed air and soil samples, looked into whether insects could be the culprit and considered a range of toxic chemicals and the possibility of electromagnetic waves", finding nothing. The American government did not cooperate with the investigation. Cuban citizens have expressed skepticism on allegations that the Cuban government orchestrated the attacks. The Cuban Foreign Minister subsequently accused the US of lying about the incident, saying "There is no evidence, there is no evidence whatsoever, of the occurrence of the alleged incidents or the cause or origin of these ailments reported by US diplomats," adding, "Neither is there any evidence suggesting that these health problems have been caused by an attack of any sort during their stay in Cuba."
On January 9, 2018, an anonymous senior United States Department of State official said that Secretary of State Rex Tillerson decided to convene a special-panel Accountability Review Board to further investigate the "attacks". On January 10, two State officials said that retired United States Ambassador to Libya Peter Bodde was tapped to lead the board.