“‘It’s the perfect kind of gray warfare.” This was how one researcher summed up the new generation of weapons that have the potential to disable people without using bullets or bombs. These are not the science fiction ‘death rays’ that have been depicted in movies and TV shows. They are very real weapons that have been demonstrated publicly or kept secret. They use sound waves, radio waves, or directed energy to attack the human body and mind.
Current reports about the capture of former Venezuelan President Nicolas Maduro have again drawn attention to this area of research, which has been shrouded in secrecy for many years. There is a reported eyewitness description of a “sonic device” causing guards to bleed from the nose and vomit blood. Although it is only anecdotal, it has a precedent in research into devices that can disable people without resorting to conventional firepower, and into strange illnesses like Havana Syndrome that have afflicted diplomats and intelligence officers around the world.
The US and other countries have been investigating acoustic weapons for many years. Devices such as the Long Range Acoustic Device (LRAD) are capable of broadcasting extremely loud sounds over a large area to disorient and, within a short range, inflict lasting hearing damage on people. Low-frequency infrasound with wavelengths and frequencies inaudible to the human ear has been researched as a tool to create nausea, dizziness, and fear in people. Although all the above effects are well-documented and well-understood, the generation of the effects associated with internal bleeding would demand significantly higher levels of energy than are currently known to be available in the field.
Another corner of this technological world is filled with microwave and radio-frequency devices. The “Havana Syndrome” incidents, first occurring in Cuba in 2016 and then in over a dozen countries around the world, raised theories of directed-energy attacks. The sufferers complained of a sudden onset of ‘pressure in the head and ear, ear pain, a sense of vertigo and difficulty concentrating their thoughts.’ Some expert groups have found pulsed electromagnetic energy a possible explanation for some incidents, while intelligence agencies have been less convinced. Still, a device secretly obtained by U.S. authorities in 2025 appeared to produce pulsed radio waves and could be carried in a backpack and consisted of foreign-manufactured parts.
There are some earlier projects that could possibly tell what could be achieved. Active Denial System works on millimeter wave radiation, which causes burning sensations on the outer skin, causing people to move away without any harm. Projects such as Electromagnetic Personnel Interdiction Control were developed with the purpose of targeting the vestibular area, which is the balance area of a person’s body, making them unable to stand. Laboratory testing has shown that pulsed microwaves could cause effects such as concussion or memory loss in animals, but developing such a technology would be a significant task.
History has its own examples. In the Cold War era, the “Moscow Signal” involved the U.S. Embassy being exposed to low-level microwave radiation. History has shown that while the results were inconclusive on health issues, it led to major research projects on the biological effects of such exposure. There have been other psychological operations that have used sound in a more crude way. Examples include the use of music to intimidate the opposition into surrendering. Such was the case during the 1989 confrontation with Panamanian leader Manuel Noriega.
Medical specialists studying patients suffering from Havana Syndrome have suggested that a possible mechanism for damage to the inner ear and brain through directed energy is “cavitation,” or the creation of tiny bubbles in a fluid near sensitive tissue. The problem for engineers is to focus sufficient energy on a target at a distance without impacting innocents or leaving traces. It is this problem, however, which also fuels the controversy over these technologies. Where a weapon may produce crippling symptoms with no apparent damage, it becomes very difficult to assign blame. This is a useful aspect of these technologies when it comes to espionage, but it is a very worrying one for the people on the other side of the conflict. One thing is certain, however, and that is that research on non-lethal human-targeting systems has never been discontinued. Whether it is crowd-control acoustics or experimental radio-frequency technologies, the science is there to affect, disrupt, or disable the human body in ways that do not necessarily engage classical defense mechanisms. Whether or not such a system is involved in the events that took place in Caracas, it is evident that it has brought back into focus how far such technology has come and how it may be employed in future conflicts.
