A mysterious illness that has caused US diplomats to suffer from dizziness, nausea and hear painfully loud chirping noises has been linked to possible "sonic attacks" by Russian spies.

       Havana Syndrome, named after the Cuban capital where it was first logged in 2016, has dogged American government employees working abroad for at least a decade.

       Operatives reported a variety of symptoms, some of which got worse depending on the direction they were facing, with the first case appearing in Cuba, but now with other cases thought to have occurred in Germany two years earlier.

       Now a joint investigation by media outlets The Insider, Der Spiegel and CBS's 60 Minutes has concluded the US officials who reported the "anomalous health incidents" (AHIs) were being targeted by Vladimir Putin-backed intelligence agents.

       So far Moscow has denied any involvement in the attacks, but if proved it would not be the first time Russian spies have aggressively acted against foreign officials in other countries.

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       In December, the British Foreign Secretary Lord David Cameron said the Russian intelligence agency, the FSB, had been using cyber attacks in a failed attempt to "interfere in UK politics".

       According to the BBC, the Havana Syndrome attacks have targeted White House, CIA and FBI staff, as well as diplomats.

       The channel says more than 1,000 reports of the illness have been made and US lawmakers are taking it so seriously legislation has been passed to support the victims.

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       The Insider, which took part in the latest investigation into the attacks, said the symptoms experienced could be the result of victims being tageted by "Non-lethal Acoustic Weapons".

       The publication said Russian intelligence operatives linked to a group known as Unit 29155 have been geolocated to places around the world which correspond with the locations of the reported mysterious illnesses, or AHIs.

       A former high-ranking CIA officer told The Insider that Unit 29155 was infamous in the intelligence community. The source said: “Their scope is global for conducting lethal operations and acts of sabotage. Their mission is to find, fix, and finish, all in support of Vladimir Putin’s imperial dreams."

       According to American officials a vareity of symptoms were experienced, including: