Photograph: Diego Grandi/Alamy Stock Photo Unexplained illnesses were first discovered among US diplomats in Havana in 2016. “It’s not something that you need to have enormous amounts of space or equipment to do it.” “You can certainly put together a system in a couple of big suitcases that will allow you to put it in a van or an SUV,” Lin, professor emeritus in the electrical and computer engineering department at the University of Illinois, said. Many of the US diplomats, spies, soldiers and officials whose symptoms are being studied as part of the Havana Syndrome investigation reported hearing strange sounds at the onset of the attacks. The pressure wave would initially be experienced by the target as sound. However, James Lin, the leading US authority on the biological impact of microwave energy, said a large apparatus would not be needed to focus energy on a small area, heating it a minute amount and causing “ a thermoelastic pressure wave” that travels through the brain, causing damage to soft tissue. They have also argued that a weapon capable of inflicting brain injury from a distance would be too unwieldy to use in urban areas. Sceptics of the microwave weapon theory have pointed to decades of US efforts to build such a device during the cold war and since, without any confirmed success. A National Academy of Sciences report in December, found that the Havana Syndrome injuries were most likely caused by “directed pulsed radio frequency energy”. The state department, CIA and Pentagon have all launched investigations, but have yet to come to conclusions. Some of the most recent incidents have involved NSC officials experiencing crippling symptoms in broad daylight in Washington. The impact on some of the victims has been debilitating and long-lasting. More than 130 US officials, from the state department, CIA and national security council (NSC), have suffered from symptoms, including dizziness, loss of balance, nausea and headaches, first identified in Cuba. If a US adversary has succeeded in miniaturising the directed energy technology needed to inflict tissue damage from a distance, it makes such weapons a more plausible explanation for Havana Syndrome. “This was important – and rather frightening – to us, because it represented a state of advancement and sophistication of these types of instruments that heretofore had not been thought to be accomplished,” he said. Giordano is restricted from giving details on which country had developed what kind of device but he said the new weapons used microwave frequencies, able to disrupt brain function without any burning sensation. A second major wave of brain injuries among US diplomats and intelligence officers took place in China in 2018. “It became clear that some of the work that was conducted in the former Soviet Union was taken up again by Russia and its satellite proxies,” Giordano said, adding that China had also developed directed energy devices to test the structure of various materials, with technology which could be adapted to weapons.

He later took part in an assessment for US Special Forces Command on which countries were developing the technology and what they had achieved. Giordano, who is also senior fellow in biotechnology, biosecurity and ethics at the US Naval War College, was brought in as adviser by the government in late 2016 after about two dozen US diplomats began falling sick in Havana. “The state of that science has for the most part been, if not abandoned, pretty much left fallow in the United States – but it has not been fallow elsewhere,” said James Giordano, professor of neurology and ethics at Georgetown University Medical Center. Scientists with knowledge of the project said that ethical considerations preventing human experimentation contributed to the project being shelved – but they said such consideration had not hindered US adversaries, including Russia, and possibly China. There is no evidence that the research was taken beyond the prototype phase, and a report on that stage has been removed from a US navy website.

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