The findings leave open the possibility that illness reported by US diplomatic staff could have been the work of adversaries.
A panel of technical and medical experts convened by the US intelligence apparatus have found that some cases of so-called “Havana Syndrome” may be caused by directed electromagnetic energy.
The findings released on Wednesday shed further light on the mysterious illness – an uncommon mix of ear pains, vertigo, nausea – that hundreds of US diplomatic workers have reported around the world.
They also leave open the possibility that the illness, at least in a few cases, could be a deliberate attack by a US adversary.
Eric Lander, director of the White House Office of Science and Technology Policy, said in a statement on Wednesday that the panel worked for nearly nine months and was the first of several expert groups to have such extensive access “to intelligence reporting and patient data”.
Out of hundreds of cases reported, “a subset of AHIs [anomalous health incidents] cannot be easily explained by known environmental or medical conditions and could be due to external stimuli,” said an unclassified summary of the experts’ report, released by the US director of national intelligence.
The experts said it is possible to create concealable devices that, using moderate amounts of energy, would direct electromagnetic energy or ultrasound waves to cause damage in a targeted person. The experts did not seek to determine if that technology currently exists or which actors may have used it.
The findings add to a previous report by a National Academy of Sciences committee, commissioned by the US State Department, which found that “directed, pulsed radio-frequency energy appears to be the most plausible” explanation for the symptoms.
It also comes weeks after the US Central Intelligence Agency (CIA) concluded that only about two dozen cases of the ailment – out of about 1,000 officially reported – did not have conventional medical or environmental explanations.
The findings appeared to douse theories that the cases were part of a worldwide attack by an adversary. The CIA did not rule out attacks by a foreign adversary as the cause of the two dozen unexplained cases.
Employees with “Havana Syndrome” symptoms have been reported at US diplomatic facilities in Australia, Austria, China, Colombia, Germany, Russia and most recently in France and Switzerland.
The symptoms were first reported in Havana, Cuba in 2016.
The experts who conducted the most recent report for the intelligence community rejected other theories of causes, including ionising radiation, chemical and biological agents, infrasound, audible sound, ultrasound propagated over large distances, and bulk heating from electromagnetic energy.
The administration of President Joe Biden has been under increased pressure from the US diplomatic community to fully investigate the sicknesses, with some accusing the State Department of downplaying the issue.
In a speech in November, Secretary of State Antony Blinken pledged to “seriously” tackle the “anomalous health incidents”, calling the issue an “urgent priority” for the department.