A directed energy attack may be the cause of the mysterious so-called Havana Syndrome, which has affected the health of US intelligence officers and diplomats since 2016.
This peculiar illness usually involves an uncommon mix of ear pains, vertigo and nausea, which hundreds of US diplomatic workers and their families have reported around the world.
The latest report from the US Intelligence Community has fuelled more speculation after revealing that directed energy "plausibly explains" some of the cases, some of which could have been caused by a concealed device.
Forces News asked two leading academics what they think about the syndrome – first reported at the US Embassy in Havana, Cuba, in 2016.
Professor James Lin, an electrical engineering expert from the University of Illinois, said: "The diplomats in Havana, Cuba, were experiencing some intense sonic sensations, loud voices, and so forth.
"They were at a loss, in fact, they describe it as a mystery, because they could not find any causes that they could understand that is making it happen."
Reports of the mystery illness, now in the hundreds, span the entire globe and have left a lasting impact on the US's ability to operate abroad.
The US has struggled to find hard evidence tying Havana Syndrome down; some think it is a weapon, others think it is all in the mind.
Dr Robert Bartholomew is an Honorary Senior Lecturer in the Department of Psychological Medicine at the University of Auckland.
He said: "I've spent 35 years of my life in my academic career specialising in mass psychogenic illness.
"This is a classic standard outbreak of mass psychogenic illness.
"The real difficulty with this outbreak is you've got bad journalism – in many areas, not all, but many – bad government and bad science," he added.
These recent findings highlighting the plausible directed energy attack have shed further light on the mysterious illness, leaving open the possibility that the illness, at least in some cases, could be a deliberate attack by a US adversary.
Professor Lin conceded that until a "culprit" is found they really do not know the cause, but "based on what we know... this is the most plausible scientific explanation".