About 100 CIA officers and family members are among some 200 US officials and family members affected by "Havana syndrome," CIA Director William Burns said.
Burns said in a National Public Radio interview that he has bolstered his agency's efforts to determine the cause of the syndrome and what is responsible.
He confirmed that among other steps, he tapped a senior officer who once led the hunt for Osama bin Laden to head a task force investigating the syndrome, and said he tripled the size of the medical team involved in the probe.
The agency also has shortened from eight weeks to two weeks the time that CIA-affiliated people must wait for admission to Walter Reed National Military Medical Center, he said.
"It's a profound obligation I think of any leader to take care of your people and that is what I am determined to do," Burns told NPR in his first interview since becoming CIA director in March.
Havana Syndrome, with symptoms such as dizzines, nausea, migraines and memory lapses, is so named because it first was reported by U.S. officials based in the U.S. embassy in Cuba in 2016.
Burns noted that a U.S. National Academy of Sciences panel in December found that a plausible theory is that "directed energy" beams caused the syndrome.
There is a "very strong possibility" that the syndrome is intentionally caused, and that Russia could be responsible, he said, adding that he is withholding definitive conclusions pending further investigation.
Moscow denies involvement.
What is Havana Syndrome?
While the cause of this mysterious illness is being investigated, victims who have Havana Syndrome hear a loud noise and feel an intense pressure or vibration in their head, dizziness and pain in their ear.
It's weird that some of the victims revealed they felt their symptoms stopped when they went to another room and returned when they went back to the same spot where they first experienced the symptoms. Some have even experienced chronic insomnia, headaches, and even brain damage, according to reports.
Reportedly, the Vienna State Department is currently looking into new reports of the mysterious illness. However, details of the same are yet to be revealed. Many US diplomats in Vienna have complained about the symptoms of the mysterious illness lately.
An intensive investigation has been launched to find the cause of unexplained health incidents among American personnel. A panel of experts led by senior intelligence officers has met in recent weeks on the mysterious "Havana syndrome" to discuss methods of identifying the cause and potential mechanisms of the mysterious illnesses.
Senior officers from the Office of the Director of National Intelligence and the CIA including scientific experts from outside government who are already cleared to access classified material are working together on the case. Meanwhile, the Austrian authorities have also considered the matter seriously and have started working on a solution despite not knowing the exact source of the problem.
"The intelligence community has convened a panel of experts from across the U.S. government and private sector to work collectively to increase understanding of the possible mechanisms that are causing these anomalous health incidents," an intelligence official told media, according to reports.
The panel was set up by President Joe Biden last month to study the strange sensory phenomenon that has baffled and concerned the government since 2016 when US diplomats in Cuba became seriously ill with mysterious symptoms.