Russia is accused of using a secret "microwave weapon" to attack two CIA agents in Australia as part of a worldwide campaign that has allegedly caused brain injuries to diplomats and spies.
The so-called Havana Syndrome has been reported for years after American diplomats stationed in Cuba suddenly started hearing strange chirping and grating noises that always occurred while they were at home or in hotels.
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What happened next was terrifying, with victims suffering headaches, memory and hearing loss, and difficulty sleeping for years. Some have become wheelchair-bound while others have been forced to wear weighted vests to correct their balance.
But it's the first time that the mysterious attacks have been reported on Australian soil.
According to a report in GQ magazine, The Mystery of the Immaculate Concussion, one of the two US agents who believe they were attacked is so senior he is among the top five highest ranking officials in the CIA.
Journalist Julia Ioffe said the two men were in Australia to hold talks with ASIO and other intelligence agencies under the Five Eyes intelligence-sharing alliance with the US, the UK, Canada and New Zealand.
"In the fall of 2019, two top CIA officials, both in the clandestine service, travelled to Australia to meet with officials in that country's spy agency," she wrote.
"While in their hotel rooms in Australia, both of the Americans felt it: the strange sound, the pressure in their heads, the ringing in their ears. According to these sources, they became nauseous and dizzy."
Another CIA officer, Marc Polymeropoulos, who helped run clandestine operations in Russia and Europe, claims to have been attacked in December 2017 in Russia.
He reportedly suffered severe vertigo in his hotel room in Moscow and developed debilitating migraine headaches that forced him to retire from the CIA.
"These injuries, and subsequent treatment by the US government, have been a living nightmare for these dedicated public servants and their families," said Senator Jeanne Shaheen, Democrat, of New Hampshire.
"It's obvious how a US adversary would have much to gain from the disorder, distress and division that has followed."
But critics have remained sceptical for years, suggesting "mass hysteria" was behind the Cuban reports.
Last year, a study published in the Journal of American Medicine Association found that the symptoms of the alleged victims could not be dismissed as psychosomatic.
"Among US government personnel in Havana, Cuba, with potential directional phenomena exposure … advanced brain MRI techniques revealed significant neuroimaging differences in whole brain white matter volume, regional grey and white matter volume, cerebellar tissue microstructural integrity, and functional connectivity in the auditory and visuospatial subnetworks but not in the executive control subnetwork," the study found.
"The clinical importance of these differences is uncertain and may require further study."
For the alleged victims, the fight for compensation and medical treatment continues, with the CIA still refusing to accept that Russia is involved.
In a statement to GQ, the US State Department said: "The safety and security of US personnel, their families and US citizens is our top priority. The US government has not yet determined a cause or an actor."