The Trump administration has described the 21 victims as embassy personnel or "members of the diplomatic community", but officials told the AP that numerous reported cases involved American intelligence workers under diplomatic cover.
Those reports come less than a week after the US reduced its diplomatic presence in Havana following mysterious attacks on USA personnel in Cuba.
Officials say that the U.S. Embassy in Cuba will stop processing visas for prospective Cuban travelers to the United States indefinitely. Others report they heard no sound at all, but later experienced a range of symptoms - from concussions to nausea to headaches to permanent hearing loss.
Secretary of State Rex Tillerson discussed the plan Monday with President Donald Trump, one of the officials said.
The U.S. embassy there will now halt regular visa operations for Cubans seeking to visit the United States.
The move to push out the Cuban diplomats comes after the USA made a decision to pull back its own staff from the island nation after suspicious "health attacks" in Havana left some victims with hearing loss and speech problems. We are, of course, closely monitoring and are in touch with USA, as well as Cuban authorities, and will act accordingly if anything warrants a change in our plans. Though Havana is likely to view the move as unwarranted retaliation, USA officials said the goal wasn't to punish the communist-run island, but to ensure both countries have a similar number of diplomats in each other's capitals.
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That description suggested only bona fide diplomats and their family members were struck, with no logical motivation beyond disrupting U.S. Roughly 50 Americans had been working at the embassy. "We will continue to investigate these attacks and get to the bottom of it". Three "zones", or geographic clusters of attacks, cover the homes where US diplomats live and several hotels where attacks occurred, including the historic Hotel Capri. The U.S. had raised complaints about the attacks to Cuba just days earlier through diplomatic channels.
The attacks have come to light three months after Pres. Trump announced new restrictions on Americans traveling to Cuba, including eliminating most individual, or "self-directed", travel to the island nation.
Mystery attacks of diplomatic community disrupting U.S.
"There's no reason this has to be the Cubans", the source said. In contrast, he said, in Cuba, "they have no evidence to indicate that USA travelers at risk during their visits to Cuba".
Those in the travel industry say the latest warning and concerns are overstated and will likely put a damper on what is a blossoming tourism destination.
But Tillerson noted in his statement that the United States maintains diplomatic relations with Havana, adding that "Cuba has told us it will continue to investigate these attacks and we will continue to cooperate with them in this effort".