International diplomacy is a tricky business at the best of times, but it shouldn’t involve physical danger. And yet, in 2016-17, U.S. diplomats stationed in Cuba started experiencing mysterious neurological symptoms, like headaches, irritability, difficulty reading, dizziness, loss of balance, hearing loss, anxiety, and memory and sleep problems.
In one person that might have been concerning enough, but at least 40 diplomats working out of the U.S. Embassy in Havana reported experiencing some of those symptoms, as did 14 Canadian diplomats stationed at that country’s embassy.
While speculation about what sickened all those diplomats has been rampant, researchers have been hard at work trying to determine what might have caused the illnesses.

As CNN reported , initial reports suggested “sonic attacks” were responsible for the diplomats falling ill, but now, a report from the National Academies of Sciences has found the likely culprit: directed microwave energy.
The researchers had already narrowed the possible sources of the neurological damage to four possibilities: infection, chemicals, psychological factors, or microwave energy.

“Overall, directed pulsed RF energy … appears to be the most plausible mechanism in explaining these cases among those that the committee considered,” the report stated. “The committee cannot rule out other possible mechanisms and considers it likely that a multiplicity of factors explains some cases and the differences between others.”
That the brains of U.S. diplomats were damaged is not in doubt.

Medical experts have examined the government employees affected, including using MRIs, and found “brain abnormalities,” according to a 2019 study, the BBC reported . While the medical experts were baffled by the cause at the time, they confirmed that the damage was real.
“Whatever happened was not due to a pre-existing condition, because we test for that,” said Professor Ragini Verma, one of the study’s authors, according to the BBC. “It’s not imagined, all I can say is that there is truth to be found.”
Similar incidents have occurred outside of Cuba as well.
The U.S. moved several diplomatic officials out of Guangzhou, China in 2018 after more reports of neurological symptoms. Researchers shed some light on the situation by revealing the results of a brain scan on one of the diplomats stationed in China, Mark Lenzi, CNN reported . He had experienced headaches, memory and sleep problems, and irritability, and an MRI found that he had “abnormally low” volumes in 20 regions of his brain, including those associated with memory, emotional regulation, and motor skills.
The National Academies of Sciences report does not attribute blame for the directed microwave energy, however.

State Department officials have been careful about describing the incidents as “attacks” and has emphasized that investigations around the incidents are “ongoing.”
“We’ve done a lot of work to try and identify how this all took place,” Secretary of State Mike Pompeo told NBC News. “And we continue to try and determine precisely the causation of this while doing our best to make sure we’re taking care of the health and safety of these people.”