Late in 2016, an officer of the Central Intelligence Agency stationed under diplomatic cover in Havana, Cuba, was at home when, by his account, he was hit by something he could not see. It came as a sudden, intense, directional sound — a piercing pressure, as if a beam of noise were being aimed at one side of his head — and it stopped the instant he moved out of its path. In the days that followed he developed headaches, dizziness, difficulty concentrating, ringing in the ears, a fog that would not lift. He was not the last. Over the following months, more than two dozen American personnel at the embassy in Havana, and some Canadians, reported variations of the same experience: a strange noise or sensation of pressure, often at night, often in a specific spot in a room, followed by a constellation of neurological symptoms that for some never fully resolved. The State Department drew down the embassy. The press called it a "sonic attack." It would come to be known as Havana Syndrome, and nearly a decade later it remains one of the genuinely unresolved mysteries of contemporary intelligence — a case in which the official bodies that investigated it reached, in sequence, opposite conclusions, and in which the most careful thing one can say is that nobody has proven what happened.
What makes Havana Syndrome so hard to pin down is that it has no single defining feature except the conviction of those who experienced it that something was done to them. The government's preferred term abandons the drama: Anomalous Health Incidents, AHIs — deliberately neutral, because "syndrome" implies a unified disease and "attack" implies a weapon, and neither has been established. The reported symptoms overlap with concussion: vertigo, cognitive difficulty, headache, visual and auditory disturbance, sometimes lasting hearing loss. The incidents did not stay in Havana. Similar reports came from the U.S. consulate in Guangzhou, China, in 2018, and later from Vienna, from Hanoi during a vice-presidential visit, even from near the White House. By the time the count was tallied, hundreds of cases across dozens of countries had been logged — which is itself an ambiguous fact, because a phenomenon that spreads as its name spreads is behaving the way both a real diffuse weapon campaign and a wave of anxious misattribution would behave.
Behind the statistics are specific people whose accounts are hard to wave away. Marc Polymeropoulos, a senior CIA operations officer, was in a Moscow hotel in December 2017 when he woke to violent vertigo, nausea, and a ringing in his ears; he came home with headaches that never fully left, was eventually diagnosed with a traumatic brain injury, and called what happened to him "an act of war." Mark Lenzi, a State Department security officer at the Guangzhou consulate whose job was analyzing electronic threats to diplomatic missions, described the onset as a sound like a marble circling down a metal funnel, after which he and his wife fell ill. In August 2021, two diplomats in Hanoi reported symptoms days before Vice President Kamala Harris was due to land, delaying her arrival by several hours. In Vienna that same year, more than two dozen American personnel reported incidents — enough that the CIA recalled its station chief over his handling of them. These are not anonymous entries on a tally. They are career officers, several with documented brain injuries, who are certain something physical was done to them, and that certainty is itself a fact any honest account has to weigh.
The place where it began carries a wrinkle that has never quite been resolved. The U.S. embassy in Havana had reopened in 2015 as the centerpiece of the Obama administration's historic thaw with Cuba, the first American embassy on the island in more than half a century. It was there, in late 2016 and into 2017, that the first roughly two dozen cases appeared among diplomats and intelligence officers. In September 2017 the Trump administration responded by withdrawing most of its personnel from Havana and expelling fifteen Cuban diplomats from Washington, effectively freezing the détente the embassy had been built to advance. And here is the wrinkle: Cuba, the host country and the obvious first suspect, had the strongest imaginable motive to protect that opening, not to wreck it with an attack on the very diplomats who embodied it. The original suspect never fit the original crime, which is part of why investigators were driven either toward a third party — Russia, with an interest in poisoning the thaw — or toward the possibility that there had been no attack at all. Cuba mounted its own investigation; a panel convened by the Cuban Academy of Sciences concluded there was no evidence of any attack, attributing the reports to stress and to local sources of sound such as insects, a finding easy to dismiss as self-serving and yet, in its specifics, not far from where the cricket analysis later landed.
The case that Havana Syndrome is an attack rests on a real piece of physics and a real piece of history. The physics is the microwave-auditory effect, sometimes called the Frey effect after the researcher who described it in 1961: a pulsed beam of radiofrequency energy, absorbed by tissue, can produce a thermoelastic wave the brain perceives as a click or sound originating inside the head — a sensation with no external source, directional, defeating the eardrum entirely. In 2020 a committee of the National Academies of Sciences, Engineering, and Medicine examined the most distinctive acute cases and concluded that the "most plausible mechanism" for their peculiar features — the directional sound, the sense of a localized beam — was "directed, pulsed radiofrequency energy." That is not a finding that a weapon was used; it is a finding that the symptoms are consistent with one. The committee was careful about the limits of what it had shown: the microwave-auditory effect can make a person perceive a phantom sound, but the mechanism by which non-thermal pulsed radiofrequency might inflict lasting brain injury — as opposed to a momentary sensation — has never been established, a gap that complicates the weapon case even at its most credible.
The history is the Moscow Signal. From 1953 until 1976, the Soviet Union bombarded the United States embassy in Moscow with a microwave beam in the 2.5-to-4-gigahertz range, for purposes still debated — eavesdropping, jamming, or something stranger — amid later, contested anxieties about elevated illness among the embassy's staff. The American response included Projects Pandora and Bizarre, classified programs studying whether the beam could affect the behavior and biology of the people inside, part of the same Cold War willingness to treat the nervous system as a target that this site documents under MKUltra. So the premise that a state might aim energy at diplomats is not science fiction; it is precedent. And in April 2024, a joint investigation by 60 Minutes, Der Spiegel, and The Insider gave the hypothesis its most specific form yet, linking the incidents to Unit 29155 of Russian military intelligence — a sabotage-and-assassination unit whose members, the reporters found, had received awards for work on "non-lethal acoustic weapons," a Russian term that covers radiofrequency directed-energy devices, and at least one of whom was placed near the location of an incident. To a significant faction of victims and former officials, the pattern is plain: a hostile capability exists, an adversary was present, and the people harmed were overwhelmingly intelligence and diplomatic personnel — exactly who a foreign service would target.
And yet the official intelligence community, after years and a thousand-plus cases reviewed, concluded the opposite. In March 2023, five of the seven agencies that examined the question assessed that it was "very unlikely" a foreign adversary was responsible, and the community found "no credible evidence that a foreign adversary has a weapon or collection device" capable of causing the incidents — a judgment reaffirmed in an updated December 2024 assessment. The mundane case has three pillars, each substantial. The first is acoustic: when the Havana recordings of the "attack" sound were analyzed, a 2018 JASON advisory report and a separate study by two biologists concluded the noise most likely came from a cricket — Anurogryllus celerinictus, the Indies short-tailed cricket, whose calling song matches the recording in pulse structure and spectrum. The crickets do not explain the illness, the biologists were careful to say, but they dissolve the original "sonic weapon" framing that launched the whole affair.
The second pillar is medical. In 2024, after years of intensive study, the National Institutes of Health published findings that, using advanced MRI and a battery of clinical tests, they could detect no signature of brain injury in AHI patients and no consistent difference between them and matched controls. The symptoms were often severe and real; the physical trace of an external weapon was absent. The third pillar is psychological, and it is the one victims most resent: the hypothesis of functional neurological disorder amplified by what some researchers, including the neurologist Robert Baloh and the sociologist Robert Bartholomew, describe as mass psychogenic illness — genuine, disabling symptoms produced and spread by stress, threat perception, and the very act of being told a hidden weapon may be hunting you. The objection to this explanation is not that psychogenic illness isn't real — it is — but that it has historically been the default verdict whenever institutions wish a difficult problem away, and that it conveniently relieves the employer of liability for a workplace injury.
A fourth possibility points at chemistry rather than psychology. A study commissioned on behalf of Canadian diplomats who fell ill in Havana — conducted by researchers at Dalhousie University — suggested their symptoms were consistent with low-dose exposure to organophosphate pesticides, the cholinesterase-inhibiting compounds sprayed in heavy quantities across the city during the 2016 anti-Zika mosquito-fumigation campaign. It is not a complete account either, but it is a reminder that "unexplained" is not the same as "inexplicable," and that several ordinary causes were competing to explain a symptom set broad enough to fit many of them.
The medical evidence is not merely absent; it is contradictory, and the contradiction is part of the story. In 2019, before the NIH work, a University of Pennsylvania team led by the radiologist Ragini Verma published its own analysis in JAMA of forty affected personnel and reported measurable differences in brain structure and connectivity against healthy controls — differences Verma called, at the time, "pretty jaw-dropping." Critics flagged the familiar hazard of small-sample MRI studies, in which statistical noise can pass for signal, and the 2024 NIH study, larger and more tightly controlled, found nothing of the sort. Two peer-reviewed studies in the same journal, five years apart, reached opposite conclusions about whether these brains were injured at all — which is less a resolution than a measure of how genuinely hard the question is.
The institutional response tells the same divided story. In January 2022 the CIA released an interim assessment: of roughly a thousand reported cases worldwide, it found no evidence of a sustained campaign by any foreign power, while conceding that a couple of dozen cases resisted every explanation it could offer. And in October 2021, Congress had already passed the HAVANA Act, authorizing compensation for personnel who suffered qualifying brain injuries from anomalous health incidents dating back to 2016. The United States government thereby settled into a posture that captures the whole strange affair in miniature: it does not believe an enemy weapon has been demonstrated, and it is paying the wounded anyway.
Havana Syndrome is the rare case where the evidence genuinely points in two directions at once, and the temptation to resolve it cleanly should be resisted in both directions. The dismissive resolution — "it was crickets and anxiety, case closed" — ignores the National Academies' radiofrequency finding, the documented Moscow-Signal precedent, the specific 2024 reporting on a Russian unit with directed-energy awards, and the lived reality of officers whose careers and health collapsed and who are not, as a class, suggestible hysterics. The credulous resolution — "a Russian microwave weapon is attacking Americans worldwide" — ignores that no such weapon has ever been recovered or demonstrated, that the founding "sonic" evidence turned out to be an insect, that the brain scans are clean, and that the case count ballooned in exactly the pattern a wave of misattribution produces. This is the same inflation dynamic that runs through the broader Directed-Energy Weapons & The Wildfire Theory family and the 5G Health Fears & The 5G–COVID Theory fear: a real but narrow capability, an unexplained harm, and a gap between them that the imagination fills with a super-weapon.
What is not in doubt is that the syndrome, weapon or no weapon, had entirely real consequences. It emptied an embassy, expelled diplomats, froze a historic diplomatic opening with Cuba, sharpened suspicion of Russia, consumed years of intelligence effort, and left hundreds of public servants genuinely ill and, many of them, genuinely unheard. A phenomenon can be epistemically unresolved and historically decisive at the same time. Havana Syndrome bent American foreign policy on the strength of a cause no one has been able to name — which is its own kind of warning about how a society metabolizes a fear it cannot verify.
The hardest possibility is that several things are true at once — that a handful of the early, acute Havana and Guangzhou cases may have been something deliberate and unexplained, while the great majority of the later, globally dispersed cases were conventional illness, stress, and the contagious power of a frightening name. That is an unsatisfying answer, and it satisfies no one: not the victims who want their injuries acknowledged as attacks, not the agencies that want the file closed, not the public that wants a villain or a debunking. But it may be the only answer the evidence currently supports — a syndrome that is partly a weapon we cannot find and partly a fear we cannot switch off, with the line between them still, after nearly a decade, undrawn.