What could be causing "Havana Syndrome" cases on U.S. soil?
Investigators are still working to explain the "Havana Syndrome" that has been afflicting U.S. officials with brain injuries since 2016. But progress came this month with a report on the nature of the brain injuries.
Dr. David Relman, a professor of medicine at Stanford University, helped lead two government-sponsored panels that investigated the injuries.
"What we found was, we thought, clear evidence of an injury to the auditory and vestibular system of the brain," Relman said. "Everything, starting with the inner ear where humans perceive sound and sense balance and then translate those perceptions into brain electrical signals."
Relman's committees found that evidence in a subset of patients whose experiences seemed inexplicable.
"This subset of cases had a very unusual, so-called 'acute sensory event,'" Relman said, "an experience that consisted of the abrupt onset of intense pressure or vibration in the face or head sometimes with the abrupt onset of sound."
Pressure and sound like that was described by the targeted officials who spoke to 60 Minutes. They said the sound, or a feeling of pressure, came from one direction and focused in one location.
"They left, it dissipated. They returned, it recurred," Relman said. "That to us was something that we had never heard of, we could not explain by known medical or environmental conditions, and to us deserved our special attention in an effort to understand what might be the plausible mechanism."
That mechanism, Relman's committees concluded, could most likely be "pulsed electromagnetic energy." In other words, a focused beam of microwaves fired from a distance.
The intelligence community investigation is also trying to understand who could be behind this and their motive. Microwaves can be a tool for spies. Some devices are capable of collecting data, remotely, from phones and computers.
Whatever is causing the brain injuries, a CIA interim report last month said there is no evidence of a massive, global, campaign to attack Americans. CIA Director William Burns told 60 Minutes that doesn't mean some of the "Havana Syndrome" cases aren't the work of a hostile actor, they just don't know.
"The intelligence community assesses now that there's not a single cause that-- would explain the more than 1,000 incidents that have been reported since Havana in 2016," Burns said. "We've also not yet been able to link a foreign state actor or an external device or mechanism to any of those cases."
Former Homeland Security Chief of Staff Miles Taylor told 60 Minutes he believes he was targeted in two mysterious incidents at his Washington home. Burns stressed it would be a profound violation if a hostile actor was behind the incidents, still, at this point, his agency doesn't have any final answers.
"We're not at a position yet where we can offer hard evidence that would connect all those dots," Burns said. "But as I said, we're not done yet. We still have a lotta work to do. And what I've said directly to a number of those officers is my promise, is that I am absolutely committed to exhausting every alternative so that we can provide the kind of answers that we owe them."