A Russian intelligence unit is probably the origin of mysterious so-called Havana syndrome symptoms – including brain injuries and hearing loss – experienced by US diplomats in recent years, according to a joint media investigation released on Sunday. The findings directly contradict the conclusion of US officials a year ago that “anomalous health incidents” (AHIs) among embassy staff in Cuba, China and various locations in Europe were not caused by an energy weapon or foreign adversary. In a related development on Monday, the US defense department said a senior official who attended a summit on international military alliance Nato at Vilnius, Lithuania, last year experienced similar symptoms. New evidence uncovered in the joint report by the Insider, Der Spiegel and CBS’s 60 Minutes – after a year-long investigation – suggests that sonic weaponry created and employed by Unit 29155 of the Russian GRU was probably the cause of Havana syndrome. The notorious unit is responsible for Russia’s military intelligence operations overseas and has been blamed for several international incidents, including the attempted poisoning of the defector Sergei Skripal in the UK in 2018. Havana syndrome was first reported in 2016 when diplomats in Cuba’s capital reported hearing piercing sounds at night, followed by staff in other locations globally, and in Washington DC. Their symptoms included bloody noses, headaches, vision problems and other strange auditory sensations. “Members of the Kremlin’s infamous military intelligence sabotage squad have been placed at the scene of suspected attacks on overseas US government personnel and their family members, leading victims to question what Washington knows,” the report states. “Havana syndrome shows all the markings of a Russian hybrid warfare operation. If it is established that the Kremlin really is behind the attacks … such a sustained, decade-long campaign would easily count as one of Vladimir Putin’s greatest strategic victories against the US.” The Insider said senior members of the unit received awards and political promotions for work related to the development of “non-lethal acoustic weapons” that include both sound and radio frequency-based directed energy devices. The report also documents numerous incidents in which senior US staff were harmed and “neutralized”, some suffering life-changing injuries that led to their premature retirements or return to the US. The American Foreign Service Association acknowledged in 2022 that Havana syndrome had “dramatically hurt” morale among US diplomats and had affected recruitment. A follow-up report on Monday from the Insider, 60 Minutes and Der Spiegel recounted how a Russian spy who worked as an executive chef at Russia-themed restaurants in New York City and Washington DC was arrested in 2020 and then interrogated by an FBI agent who later came down with Havana syndrome. The outlets that produced the report again posited that the agent’s symptoms may have been caused by a directed energy weapon wielded by the GRU. In March last year, however, the joint conclusion of seven US intelligence agencies – in a redacted report following their own multi-year investigation into AHIs – was that “available intelligence consistently points against the involvement of US adversaries in causing the reported incidents”. Five of the agencies said foreign involvement was “very unlikely”, one found it “unlikely”, and the seventh declined to offer an opinion. But most noted their assessments were moderate to low confidence given the available evidence. On Monday, Russia dismissed as “baseless” the new report linking attacks to its military intelligence operations. “This is not a new topic. For many years so-called Havana syndrome has been exaggerated in the press, and from the very beginning it was linked to accusations against the Russian side,” the Kremlin press official Dmitry Peskov told reporters. “But no one has ever published or expressed any convincing evidence of these unfounded accusations anywhere. Therefore, all this is nothing more than baseless, unfounded accusations by the media.” Also on Monday, a Pentagon spokesperson, Sabrina Singh, told reporters that an unnamed senior defense department official experienced Havana syndrome symptoms during a 2023 Nato summit in Vilnius. Citing medical privacy laws, she did not say if the official required treatment, or had to cease performing their duties. The US closed its Havana immigration office in 2018 under an American policy shift toward Cuba and also in response to fears at the time that the Havana syndrome was a result of a microwave or other electronic attack. It reopened in August 2023, almost half a year after the US report found no credible evidence that Russia, or anybody else, was behind the attacks. The new Insider report suggests the first cases may have occurred in Germany two years earlier than those in Havana in 2016 that gave the syndrome its name. “There were likely attacks two years earlier in Frankfurt, Germany, when a US government employee stationed at the consulate there was knocked unconscious by something akin to a strong energy beam,” the report said. The New Yorker reported in July 2021 that about two dozen US intelligence officers, diplomats and other government officials in Austria had reported problems similar to Havana syndrome since Joe Biden became president the same year. The US deployed medical and scientific experts to study the alleged attacks and those affected have been extensively examined to try to understand their afflictions. In 2021, Congress passed the Havana Act, authorizing the state department, CIA and other government agencies to provide payments to staff and their families who were affected during assignments. “We are working overtime across the entire government to get to the bottom of what happened, who’s responsible. And in the meantime to make sure that we’re caring for anyone who’s been affected and to protect all of our people to the best of our ability,” the US secretary of state, Antony Blinken, said in 2022 after further cases were reported in Paris and Geneva. CBS said in a tweet that the office of the director of national intelligence referred inquiries by 60 Minutes journalists to the intelligence community’s annual threat assessment commentary on AHIs. The network obtained statements from the White House and FBI promising to continue to investigate the causes and consequences of AHIs.