The US Embassy in Cuba stopped issuing visas on Friday, following fears that even more of its personnel could be harmed. Speaking to CNN, officials confirmed that as many as 21 US diplomats and their families began suffering after the Presidential election took place last year.

No actual device or weapon has been found since the attacks began. However, US officials told CNN they are being “specifically targeted with a sophisticated device never deployed before,” at least, not against Americans. Those under attack have suffered an array of symptoms including, concussions, hearing loss, nausea, and dizziness. Investigators say the sound waves in question are too faint to be heard by the human ear.

But, they note that they can have disastrous consequences when focused on someone or a group.

No progress made

Since the US raised their concerns with the Cuban Government last year, Cuba has vehemently denied any responsibility for the attacks. Instead, Cuban Foreign Minister Bruno Rodríguez said on Tuesday 26, that America was “politicizing the incidents”. He promised, however, to “continue working with US authorities investigating the attacks”. Some investigators have considered the possibility of a foreign Government being behind the attacks. But to date, no evidence has been discovered to support their theory.

Options available to the US

The safety of its citizens is not something the US has ever taken lightly. Speaking to CNN, three senior US officials said shutting down operations in Cuba is highly likely.

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They noted that after a year of complaints and investigations, no progress had been made and even Canadian diplomats and their families had been attacked in June. The situation is undoubtedly becoming more serious and measures need to be put in place. Some US Embassy staff have refused to leave Cuba, saying they did not want to “play into the hands of whoever was responsible” and give him/her the satisfaction of victory. It is a crucial time in Cuba and President Raul Castro is expected to step down soon. The US says it does not want its Embassy understaffed at such a critical time. Nevertheless, in protecting its people, the US says it might still scale back operations, depending on whether the attacks continue. The most recent sonic attack occurred in August and CNN says as many as 50 incidents overall, are believed to have taken place since November 2016.

Strained relations

Cuba has generally had a strained relationship with the US. But former President Barack Obama tried to heal their divisions by agreeing to restore full diplomatic relations in 2016. In the wake of the latest mystery attacks, however, his efforts might have been in vain. In an address to the UN General Assembly in September, President Trump was adamant that he would not "lift sanctions on the Cuban Government until it makes fundamental reforms." In June, he also blasted Cuba for "repressing human rights and political freedoms".