STRANGE symptoms that afflicted American and Canadian officials in Cuba three years ago - becoming known as the “Havana Syndrome" - have been reported around the world, with speculation growing over possible foreign attacks.

What happened?

In August 2017, reports emerged that US and Canadian diplomatic officials in Cuba had been suffering from a range of health issues, including dizziness and headaches, in episodes that dated back to October 2016. Victims reported hearing grating noises, with some experiencing said noise as a vibration they compared to driving with the window down. The sensations were always experienced while the victims were in their hotel rooms or at home.

Some symptoms were severe?

One US diplomat reported being jolted awake in his Havana hotel room by a “blaring” noise that disappeared when he moved away from his bed, deafening him again when he got back into bed. He suffered hearing loss and speech problems. Others reported memory, concentration and balance problems, as well as nose bleeds and tinnitus.

What caused the incidents?

The US said at the time that it held Cuba “responsible for finding out who is carrying out these health attacks”, with the allegation being that diplomats had been targeted with an acoustic weapon in a series of “sonic attacks”. No evidence of any such attack has been verified.

What did Cuba say?

A statement declared that "Cuba has never, nor would it ever, allow that the Cuban territory be used for any action against accredited diplomatic agents or their families, without exception” and the question of Russian involvement quickly arose. The attacks came around the time the US was accusing Russia of interfering in the US election with Barack Obama expelling 35 Russian diplomats.

However?

Last year, a report in the Journal of the Royal Society of Medicine suggested the symptoms of “Havana Syndrome” were caused by “emotional trauma and fear”.

The “Moscow Signal”?

In a classic Cold War episode, the "Moscow Signal" was the name given by US intelligence officials to describe the alleged microwave transmission directed at the US Embassy in Moscow from 1953 to 1976. Between 2.5 to 4 gigahertz was directed at the embassy in what the US government concluded was an espionage effort, with the resulting health impact on embassy staff a side effect. 

CIA?

Two CIA agents reported symptoms consistent with “Havana Syndrome” while visiting Australia late last year. According to a report in America's GQ magazine, mobile phone data showed Russian agents were in the vicinity of their hotel room at the time. The CIA agents reported experiencing a similar episode when they travelled on to Taiwan. Another CIA officer reported suffering severe vertigo in his Moscow hotel room in December 2017, later retiring due to migraines.

China?

In the spring of 2018, more than a dozen US diplomatic staff and their family members in China reported hearing strange sounds, blurred vision, memory loss, dizziness and headaches. However, whereas after Cuba, US staff were withdrawn by the Trump Administration, the New York Times reports that amid concerns for diplomatic relations between China and America, US staff in China had to use sick days and unpaid leave for rehabilitation.

It comes as?

Reports have emerged this week that President Trump has a secret Chinese bank account and spent years pursuing business interests in the country.

Now?

Calls are being made for a State Department report into the potential causes of the Chinese incidents to be released. The department said “US government has not yet determined a cause or an actor”.