Pulsed electromagnetic energy, ultrasound ‘plausibly’ explains Havana syndrome

Enlarge / Photo of the US Embassy in Havana, taken on September 29, 2017, after the US announced it was withdrawing more than half of its staff in response to mysterious ‘health attacks’ targeting its staff diplomatic.

A device delivering pulsed electromagnetic energy or ultrasound “plausibly explains” the puzzling health incidents that have caused debilitating and long-lasting neurological effects in some US diplomats and intelligence agents. That’s according to a report by a panel of intelligence community analysts and outside experts in the fields of science, medicine and engineering. An executive summary of the report was declassified and released on Wednesday.

The new report is the latest effort to unravel a medical mystery that began in 2016 when US and Canadian diplomats stationed in Havana, Cuba, reported bizarre and unexplained episodes. Diplomats described piercing, directional sounds and vibrations that left them with a constellation of neurological symptoms, sometimes referred to as “Havana syndrome.” Since then, hundreds of additional possible cases among US intelligence officers stationed around the world have poured in, fueling widespread speculation, skepticism and political controversy.

The new report reinforces a key but controversial hypothesis: that the incidents are attacks by a foreign adversary – primarily believed to be Russia – using a covert weapon, possibly one that delivers pulsed radiofrequency energy. While some analysts and experts have openly dismissed the idea, the panel concludes that pulsed electromagnetic energy or ultrasound are plausible causes. However, the panel did not consider who might be responsible.

Overall, the report is far from any definitive conclusion. The executive summary that was released includes numerous redactions and notes that there are caveats and “information gaps” about plausible scenarios. There is still no solid evidence that such a weapon exists or has been used against US personnel. And whether such attacks occurred, the motive is also unclear (although there is much speculation).

Still, the panel worked to narrow the possibilities and concluded that other popular hypotheses about the cause of the mysterious health incidents are unlikely. Improbable theories include functional neurological disorders and mass psychogenic diseases (collective delusion). The panel also questioned ionizing radiation, audible sounds (sonic weapons or locusts), and chemical and biological agents.

“These mechanisms are unlikely, on their own, to account for the required effects or are technically or practically unfeasible,” the expert group concluded.


Together, the new report reinforces the findings of a 2020 report from the National Academies of Sciences, Engineering, and Medicine. The 2020 report concluded that directed pulsed radiofrequency energy was the “most plausible mechanism” to explain the cases. The new report also echoes the findings of a team of doctors from the University of Pennsylvania who examined 21 affected US personnel and ruled out mass psychogenic illness. The doctors concluded in a 2018 JAMA article that the staff had “experienced damage to extensive brain networks with no associated history of head trauma”. But their wounds and experiences were incompatible with a mass psychogenic illness, and not all individuals were in contact with each other, which would be necessary for a collective delusion to spread. The team also dismissed viral and chemical agents as possible explanations.

The new report is also consistent with an interim CIA report released two weeks ago. This report concluded that, of approximately 1,000 reports of possible health incidents among intelligence and State Department employees, most were easily explained by known environmental or medical factors. Thus, the CIA concluded that it was unlikely that a foreign adversary, such as Russia, would orchestrate any kind of sustained global campaign against American personnel. However, a few dozen cases remain unexplained, and the CIA has left open the possibility that adversary attacks may be behind them.

These remaining unexplained cases are the focus of the expert panel’s new report. To dig deeper into these cases, the panel went through dozens of briefings and more than 1,000 classified documents, which covered scientific and medical topics, including sensitive intelligence reports, health incident reports and trend analysis. The panel also had direct access to US personnel with unexplained cases and their medical records.

The panel concluded that, in these cases, the signs and symptoms of the incidents – which the government calls AHI (abnormal health incidents) – were “genuine and convincing”. Overall, AHIs are marked by four consistent characteristics:

  1. Acute onset of audio-vestibular sensory phenomena, sometimes including sound or pressure in only one ear or on one side of the head
  2. Other near-simultaneous signs and symptoms such as dizziness, loss of balance, and ear pain
  3. A strong sense of locality or directionality
  4. And the absence of known environmental or medical conditions that could have caused the reported signs and symptoms

The panel said some incidents affected multiple people in the same space and that clinical samples from some of those affected showed biomarkers of “nervous system cellular damage”.

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