The Defense Department has spent more than a year testing equipment purchased during a covert operation that some investigators believe may be the cause of a mysterious series of illnesses affecting U.S. spies, diplomats and troops known colloquially as Havana syndrome, according to four people familiar with the matter.
Homeland Security Investigations, a division of the Department of Homeland Security, spent millions of dollars purchasing the equipment with funding from the Defense Department during the waning days of the Biden administration, according to two sources. Officials paid “eight figures” for the equipment, these people said, declining to provide a more specific figure.
The device is still under study, and there has been debate and skepticism among some quarters in the government over its link to perhaps dozens of unusual health events that officials have yet to explain.
CNN has requested comment from the Pentagon, the Department of Homeland Security and the Department of Homeland Security. The CIA declined to comment.
One of the sources said the equipment acquired by HSI produces pulsed radio waves, which some officials and academics have speculated for years as a possible cause of the accident. The person added that while the device was not entirely of Russian origin, it contained Russian components.
Officials have long struggled to understand how a device powerful enough to cause the kind of damage reported by some victims could be made portable. According to a source with knowledge of the device, this remains a core issue. The person said the device could be carried in a backpack.
The acquisition of the device has reignited the painful and contentious debate within the U.S. government over Havana syndrome, officially known as “unusual health episodes.”
The mysterious illness first emerged in late 2016, when a group of U.S. diplomats stationed in the Cuban capital, Havana, began reporting symptoms consistent with head trauma, including dizziness and extreme headaches. In the following years, such cases were reported around the world.
Over the next decade, the intelligence community and the Department of Defense tried to understand whether these officials were the victims of some kind of directed energy attack by a foreign government—senior intelligence officials publicly stated that there was insufficient evidence to support this conclusion, and that the victims believed that the U.S. government had gaslighted them and ignored important evidence that Russia was attacking U.S. government officials.
Still, defense officials considered their findings serious enough that they briefed the House and Senate intelligence committees late last year, including mention of the equipment obtained and its testing.
A major concern among some officials now is that if the technology proves viable, it could proliferate, meaning more than one country would now have access to a device that could harm the careers of U.S. officials, some sources said.
CNN was unable to learn where or from whom HSI purchased the equipment, but HSI has a history of working with the Department of Defense to conduct operations around the world. The office has broad jurisdiction to investigate crimes related to customs violations, including investigating the spread of U.S.-controlled technology or expertise overseas.
One former DHS official said the investigations were “the single largest point of cooperation between Homeland Security Investigations and the U.S. military.”
For example, the official said, HSI is called upon when the U.S. military discovers U.S. technology in Afghanistan or Iraq and has questions about how those components got into the region.
It’s unclear how the U.S. government learned of the device’s existence and purchased it. Havana Syndrome and its causes remain frustratingly opaque to the intelligence and medical communities.
One problem facing the medical community is that there is still no clear definition of “abnormal health events” or AHIs. In some cases, testing is done long after symptoms appear, making it harder to understand what’s going on physically.
In 2022, an intelligence team investigating the causes of AHI said it “appears” that some events may have been caused by “pulsed electromagnetic energy” emitted by an external source.
But in 2023, the intelligence community publicly stated that it could not link any cases to foreign adversaries and ruled that the unexplained illness was unlikely to be the result of targeted actions by U.S. enemies. As recently as January 2025, the broader intelligence community assessment remained that the symptoms were unlikely to have been caused by a foreign actor—although an official in the Office of the Director of National Intelligence stressed that analysts could not “rule out” that possibility in a handful of cases.
That stance has long angered victims, many of whom are convinced the intelligence provided black and white evidence that Russia was behind their symptoms, some of which were severe enough to force them into retirement.
CNN previously reported that some current and former CIA officials have expressed concerns about the agency’s de-escalation of investigations.
Some victims view obtaining the device as potential vindication.
“if [US government] Mark Polimeropoulos was one of the first CIA officials to publicly acknowledge that he was wounded in the 2017 attack on Moscow, he said in a statement to CNN.
CNN’s Kylie Atwood contributed to this article.
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