An intelligence panel was investigating the cause of a series of mysterious incidents, known colloquially as “Havana Syndrome“, that have struck dozens of US officials around the world. As per the executive summary of the panel’s findings released Wednesday, some of the episodes could “plausibly” have been caused by “pulsed electromagnetic energy” emitted by an external source.

The panel, however, stopped short of making a definitive conclusion, stating only that electromagnetic energy and, in limited circumstances, ultrasound could explain the key symptoms, highlighting the extent to which the enigmatic illness has remained one of the intelligence community’s most vexing mysteries.

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“We’ve learned a lot,” according to a source familiar with the panel’s work who spoke to CNN on the condition of anonymity because of the Office of the Director of National Intelligence’s restrictions. “While we don’t have the specific mechanism for each case, what we do know is if you report quickly and promptly get medical care, most people are getting well.”

The discovery generally backs up a National Academies of Science research from late 2020, which deemed “directed, pulsed radio frequency energy” to be “the most plausible mechanism in explaining these cases,” but stopped short of making a definitive statement.

The so-called experts panel is made up of medical, scientific, and engineering professionals who have access to confidential incident information. Officials stressed that their investigation was limited to determining the process behind what the government refers to as “anomalous health incidents,” not who, if anyone, might be to blame.

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According to a preliminary report released last month by a separate CIA task team looking into who might be behind the incidents, it’s doubtful that Russia or any other foreign enemy is waging a global campaign to attack US officials. However, the agency would not rule out the possibility that a nation state, such as Russia, is to blame for the roughly two dozen cases that investigators have been unable to link to any other known source.

The scientific group stressed that the cases it looked at were “genuine and compelling,” adding that some incidents affected numerous people in the same space and that clinical samples from a few victims showed signs of “cellular injury to the nervous system.”

An executive summary of the panel’s report revealed fresh information about how the government classifies cases. Havana Syndrome is a clinically obscure sickness that has long eluded accurate identification due to the wide range of symptoms experienced by victims.

Officials wouldn’t say how many cases the panel looked into, but they did say they looked into cases that had four “core characteristics”: acute onset of sounds or pressure, sometimes in only one ear or on one side of the head; simultaneous symptoms of vertigo, loss of balance, and ear pain; “a strong sense of locality or directionality”; and the absence of any known environmental or medical conditions that could have caused the other symptoms.

This confluence of symptoms has hit victims at embassies and private residences around the world, as well as at least one open-air stoplight in a foreign country.

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The panel discovered that pulsed electromagnetic waves, “particularly in the radiofrequency range,” as well as ultrasonic arrays, could potentially induce the four primary symptoms. Both could have come from “a concealable source.” However, ultrasound can’t go through walls, according to the panel, so it’s only useful in situations where the source is close to the target.

Radiofrequency energy sources, on the other hand, are well-known, “could generate the required stimulus, are concealable, and have moderate power requirements,” according to the panel. “Using nonstandard antennas and techniques, the signals could be propagated with low loss through air for tens to hundreds of meters, and with some loss, through most building materials.”

However, intelligence officials acquainted with the panel’s work pointed out that significant information gaps still exist, preventing them from making more certain findings.

“It’s frustrating but we’re just as persistent to help understand and elucidate what’s happening,” one official said.

Part of the problem, according to this person, is that not only do the instances differ, but the combination of the four fundamental traits is unique in medical literature.

“When we focus on the core characteristics, it’s just a unique combination that we don’t have a lot of experience with in the medical and clinical fields,” the official said.

Furthermore, there has been little research into the effects of radiofrequency energy or ultrasound on the human body due to ethical concerns. The experts’ panel was limited to testimonies from those who had been “inadvertently” exposed to either and were willing to describe their symptoms.

“There is a dearth of systematic research on the effects of the relevant electromagnetic signals on humans,” the executive summary of the report stated.

The experts panel also ruled out one cause for those four characteristics: so-called psycho-social elements, which was a success for victims’ supporters. Some victims have long complained that the CIA has ignored their reported symptoms, dismissing them as a psychosomatic event or mass hysteria in the past.

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The research showed that psychosocial variables could not explain those four key traits “alone,” while one intelligence officer explained that in some situations, a victim’s symptoms could be “compounded” by a stress reaction or other psychosocial response.

The panel also ruled out “ionizing radiation, chemical and biological agents, infrasound, audible sound, ultrasound propagated over large distances, and bulk heating from electromagnetic energy.”

The panel issued seven recommendations, including the creation of stronger biomarkers that are “more specific and sensitive for case diagnosis and triage.” It also suggested getting “devices to aid research” and using “detectors.” In the panel’s executive summary, the details of those recommendations were largely suppressed.

Finally, officials asked medical officials to act quickly if a case is reported, highlighting that people who have been treated quickly after an occurrence have fared better.

“I think something the employee can do to help themselves is promptly report and get medical care,” the intelligence official said.

The intelligence community will continue to investigate, according to officials.

“We continue to pursue complementary efforts to get to the bottom of Anomalous Health Incidents — and to deliver access to world-class care for those affected,” Avril Haines, the Director of National Intelligence, and Bill Burns, the Director of the Central Intelligence Agency, issued a joint statement.  “We are making progress in both areas.”