Washington(CNN) President Donald Trump said Monday that he does "believe Cuba is responsible" for the mysterious attacks that sickened at least 22 US diplomats and family members in Havana.
"I do believe Cuba's responsible, I do believe that," Trump said in the Rose Garden.
Investigators continue to examine the circumstances surrounding as many as 50 attacks that may have involved the use of an acoustic device, a US official has told CNN.
The device was so sophisticated, it was outside the range of audible sound, the official said. And it was so damaging, the source said, that one US diplomat now needs to use a hearing aid.
Three US officials told CNN that the device was deployed either inside or outside the residences of US diplomats living in Havana.
For months, starting late last year, US diplomats in Havana complained of incidents, often late at night in their homes or hotel rooms, that left them feeling ill -- often plagued by a sudden wave of nausea, dizziness and headaches accompanied by strange sounds compared to loud insects or metal dragging across the floor.
Questions also continue to swirl around the Cuban government's involvement in the attacks, given that experts say the country likely lacks the scientific expertise to launch such a sophisticated operation.
On Thursday, Trump's chief of staff, John Kelly, did not directly accuse the Cuban government of carrying out the attacks but told reporters: "We believe the government could stop the attacks on our diplomats."
"The question that nobody seems to be asking is why would the Cubans do such a thing?" Steven L. Garrett, who taught acoustics at Penn State University before retiring last year, told CNN last week.
"The Cubans are not known for sophistication in physical and engineering acoustics," Garrett said.
A US official has told CNN that they are investigating whether a third country was involved as "payback" for actions the US has taken elsewhere and to "drive a wedge between the US and Cuba."
The President did not expand on what led to the conclusion that Cuba was responsible, but called it a "very unusual attack."
Earlier this month, the US expelled 15 Cuban diplomats to match staff reductions at the US Embassy in Havana after the US ordered home non-essential diplomats and families following the mysterious attacks.
The move drew an angry rebuke from Cuban Minister of Foreign Affairs Bruno Rodríguez Parrilla.
"Cuba has never perpetrated, nor will it ever perpetrate attacks of any sort against diplomatic officials or their relatives," Rodríguez Parrilla said at a news conference in Havana.