State Department spokeswoman Heather Nauert confirmed Thursday that at least 16 individuals working at the U.S. embassy in Cuba were struck by a mysterious illness last year and experienced a range of symptoms.
The State Department had not previously disclosed how many American diplomats were affected by what Nauert described as "incidents," which she said are no longer ongoing.
"We only now have the confirmation of the number of Americans who have been affected by this," Nauert told reporters. "We can confirm that at least 16 U.S. government employees, members of our embassy community, have experienced some kind of symptoms."
"They have been provided medical treatment in the United States as well as in Cuba," Nauert added. "We take this situation extremely seriously."
American diplomats in Cuba had complained about various symptoms, including severe migraines and hearing loss, beginning in late 2016. A U.S. doctor diagnosed some with conditions as serious as mild traumatic brain injury, and with likely damage to the central nervous system, according to CBS News.
Sources had told the Washington Free Beacon earlier this month that the number of embassy workers sickened appeared to be greater than 10, but did not have an exact number.
The U.S. is investigating whether the diplomats were targets of a sonic attack. If the cause of their symptoms was a sonic attack, Cuba may not necessarily be responsible, according to sources who spoke to the Free Beacon.
"There's no reason this has to be the Cubans," said one source, a veteran foreign policy adviser who is close to the White House. "That place is a playground for some of the worst actors on the planet: Russia, Iran, Venezuela, and so on. U.S. adversaries and enemies have free rein there, which is one of the many reasons it was better to try to isolate Cuba than pretend they could be productively integrated into the international community."
The diplomats with symptoms were brought back to the United States for treatment after first receiving treatment in Cuba.
Some U.S. officials have said the Obama administration, which restored diplomatic ties between the U.S. and Cuba, may have downplayed the number of those affected by the symptoms.