The CIA has found that the majority of mysterious “Havana Syndrome” cases reported to the government are unlikely to have resulted from efforts by hostile foreign powers, a U.S. government official told HuffPost following reports by other news outlets on Thursday.
The interim assessment, however, concluded that a couple dozen cases require more study to evaluate possible foreign involvement.
Several hundred U.S. diplomats, spies and other government personnel have complained of debilitating and unexplained symptoms, which generally include migraine headaches and nausea after hearing strange noises, beginning with State Department staff at the American embassy in Cuba in 2016.
A targeted energy weapon ― perhaps using microwaves ― was speculated to be the culprit, although others say that’s unlikely based on current scientific advancements. Another theoryposits that it could be a mass psychogenic illness, or “mass hysteria,” causing the symptoms.
“Despite extensive investigation, we have so far not found evidence of state actor involvement in any incident. Taking into account all of the intelligence we have collected and reviewed at this point, we assess it is unlikely that a foreign actor, including Russia, is conducting a sustained, worldwide campaign harming U.S. personnel with a weapon or mechanism,” the U.S. official said.
The majority of known cases can be “reasonably explained” by undiagnosed medical conditions or environmental factors, said the official.
But the CIA is continuing to investigate two dozen cases and has not ruled out the possibility of foreign involvement for those. That set includes many of the original patients who complained of mysterious medical ailments in Havana six years ago, according to NBC News.
Victims of Havana Syndrome faced skepticism by officials during the administration of President Donald Trump, who displayed unusual deference to Russian President Vladimir Putin. The U.S. official stressed that CIA Director William Burns, installed by President Joe Biden last year, is committed to protecting the health and well-being of agency personnel.
Burns said in a statement that his agency is “pursuing this complex issue with analytic rigor, sound tradecraft, and compassion and have dedicated intensive resources to this challenge.”
“While we have reached some significant interim findings, we are not done. We will continue the mission to investigate these incidents and provide access to world-class care for those who need it,” Burns said.
A significant number of other cases also do not have tidy explanations, an official told The New York Times.
Senate Intelligence Committee Chair Mark Warner (D-Va.) emphasized that efforts to get to the bottom of the maladies are ongoing.
“It’s important to note that today’s assessment, while rigorously conducted, reflects only the interim work of the CIA task force,” Warner said in a statement. He added that his committee will “continue pressing for answers on a bipartisan basis” alongside the intelligence community and an “outside experts panel that has been assembled to seek answers to these very urgent and difficult questions.”
House Intelligence Committee Chair Adam Schiff (D-Calif.) called the CIA’s report “a first step” toward answering questions about Havana Syndrome, but “far from the last.”
U.S. diplomats, intelligence officers, staff and military personnel have complained of Havana Syndrome-like symptoms in Austria, China, India, Russia, Columbia ― and even in Washington, D.C. The onset of two staffers’ mysterious health complaints delayed Vice President Kamala Harris’ trip to Vietnam last year.
Aside from headaches and nausea, some victims experience memory loss and cognitive impairments that sometimes make it impossible to do their jobs.
In early October, Biden signed legislation to compensate Havana Syndrome victims and ensure they have access to proper medical care.
“We are bringing to bear the full resources of the U.S. government to make available first-class medical care to those affected and to get to the bottom of these incidents, including to determine the cause and who is responsible,” the president said at the time.
This article originally appeared on HuffPost and has been updated.