The United States announced Friday that it's permanently removing 60 percent of its diplomats from Cuba after unexplained illnesses linked to mysterious "sonic attacks" in Havana harmed at least 24 Americans.
Computer scientists at the University of Michigan, however, say they may have solved the mystery behind the strange sounds that caused a variety of medical disorders, the Miami Herald reported.
Two sources of ultrasound - such as listening devices - could generate interference and provoke the intense sounds described by the victims when they're placed too close together, according to the university's Security and Privacy Research Group. The sonic occurence "may not have been done intentionally to harm diplomats," according to the scientists' study, which was first reported by the Daily Beast.
The State Department ordered non-essential embassy personnel and the families of all staff to leave Havana in October, arguing that they could not be protected from the unexplained illnesses.
The downsizing of the embassy staff - and a warning to Americans to reconsider travel to the island - have had significant effects for Cuba's economy and for its citizens. The embassy halted visa processing, forcing Cubans visiting the United States to go through U.S. embassies in other countries.
Secretary of State Rex Tillerson approved the permanent plan for reduced staffing out of concern for "the health, safety and well-being of U.S. government personnel and family members," the State Department said in a statement Friday. Despite the Michigan study, the department maintained that "we still do not have a cause or source of the attacks" and that the "investigation is ongoing," according to the Herald.
Most of the victims said they heard a shrill sound coming from a specific direction before experiencing the ailments. Professor Kevin Fu and his team used recordings of the sound to replicate what was heard by diplomats.
The Cuban government independently investigated the incidents, concluding that nothing suspicious was found in recordings provided by U.S. agencies. Officials in Havana maintained that the sounds are similar to those produced by crickets and cicadas.