WASHINGTON — Editor's note: The related video above was published in September 2017.
Radiofrequency energy, a kind of radiation that includes microwaves, was the most likely cause for the mysterious illness that sickened U.S. officials first in Cuba, and then in China, Russia and other countries, a government study says.
The report by the National Academies of Sciences, Engineering, and Medicine says that "directed, pulsed radiofrequency energy" was "the most plausible mechanism" to explain the sickness, which came to be known as Havana syndrome, according to news outlets. NBC News and The New York Times reported Saturday that they both obtained the study commissioned by the State Department.
But the 19 experts in medicine and other fields who did the report said they could not rule out other causes and factors that could have contributed to the symptoms at least 40 federal employees experienced.
Many officials reported hearing a loud sound and feeling pressure in their head. They suffered from dizziness, fatigue, headaches and hearing and memory loss, and some were forced to retire.
The study is the most definitive explanation yet of the strange sickness that struck officials first at the U.S. Embassy in Havana in 2016, and then in China and elsewhere.
U.S. officials suspected Russia in what some thought were attacks on diplomats and other workers, but there is not conclusive intelligence supporting that. The report does not address if radiofrequency energy was intentionally delivered by a weapon, but says studies "by Western and Soviet sources" over decades have shown the illnesses could be from an attack. Russia has denied involvement in the illnesses.
In response to the study, the State Department said the cause remains speculative in the three-year-long investigation.