The U.S. intelligence community has launched a new panel of experts that brings together senior officers and outside medical and scientific experts to investigate the "anomalous health incidents" affecting dozens of U.S. personnel around the world, an intelligence official told ABC News.
The U.S. government still has not reached a conclusion into the cause of the incidents, sometimes known as "Havana syndrome" after the first cluster of cases was reported at the U.S. embassy in Cuba.
But more reported cases are now being investigated at the embassy in Austria's capital, Vienna, according to the State Department, whose spokesperson said Monday that it is "vigorously investigating reports of possible unexplained health incidents" among U.S. personnel there.
Austria is just the latest country where incidents have now been reported. The National Security Council is overseeing a government-wide review "to ascertain whether there may be previously unreported incidents that fit a broader pattern," White House press secretary Jen Psaki said Monday, and "whether they constitute an attack of some kind by a foreign actor."
Beyond that review, the intelligence community also established the new panel of experts earlier this month -- bringing together senior officers from the CIA, the Office of the Director of National Intelligence and outside scientific and medical experts -- to explore the multiple hypotheses into what is causing the "health incidents," an intelligence official told ABC News.
It's the latest federal government review into an issue that has vexed officials since 2016 when the first cases were reported in Cuba, underscoring how little U.S. officials still know about it.
The new panel will build off of the findings of a report by the National Academies of Sciences, Engineering and Medicine last December, according to the official, which concluded that "directed, pulsed radio frequency energy appears to be the most plausible mechanism in explaining these cases, especially in individuals with the distinct early symptoms."
Dozens of U.S. officials have been diagnosed with injuries, including traumatic brain injuries, after reporting strange experiences like high-pitched sounds or feelings of pressure or vibration, or debilitating symptoms including headaches, nausea, cognitive deficits, and trouble with seeing, hearing, or balancing.
Before Austria, the U.S. government had acknowledged, in public or in declassified documents, reported cases in Cuba, China, Uzbekistan, Russia, and the United States, although the White House has said "the vast majority" of cases have been reported overseas.
The top Democrat and Republican on the Senate Intelligence Committee warned in May that the "pattern of attacking our fellow citizens serving our government appears to be increasing."
"In coordination with our interagency partners, we are vigorously investigating reports of possible unexplained health incidents among the U.S. embassy community there" in Vienna, State Department spokesperson Ned Price said Monday.
The agency has declined to provide more details, including the number of affected personnel. But according to The New Yorker magazine, which first reported on the Vienna cluster, it totals around two dozen U.S. diplomats, intelligence officers and other government officials -- now second only to Havana.
A CIA spokesperson told ABC News that director Bill Burns "is personally engaged with personnel affected by anomalous health incidents and is highly committed to their care and to determining the cause of these incidents" but declined to provide more details.
Both the CIA and the State Department have elevated their internal task forces investigating reported incidents among their personnel, while the State Department has its own team of medical experts that responds to reported incidents around the world.