Claims of Microwave Attacks Are Scientifically Implausible

“It’s an act of war,” said Christopher Miller, former President Donald Trump’s last acting secretary of defense. He was talking about alleged attacks on diplomatic and intelligence personnel by an unknown microwave directed-energy weapon. But before the United States declares war on the unknown enemy wielding that weapon, we should know what it is—and whether it exists at all.

Every few weeks, another alleged attack on Americans is reported, some recent, some decades ago. The symptoms are neurological, such as dizziness, headaches, and brain damage. The first wave of reports came in 2016, from the American and Canadian diplomatic missions in Havana, hence the name “Havana syndrome.” Since then, similar cases have been reported in other places, including China; Washington, D.C.; and Syria. State Department and intelligence personnel make up most of those affected.

The State Department and the CIA have investigated Havana syndrome, with much criticism by the victims and their legal counsel. The Jasons, a group of defense advisors, have been reported to be studying the incidents. Most recently, the National Academies of Sciences, Engineering, and Medicine also conducted a study that concluded a microwave attack was the most plausible explanation; it also considered chemical pollutants, infectious agents, and psychological and social factors, and found all these explanations wanting.

Here’s the problem. Aside from the reported syndromes, there’s no evidence that a microwave weapon exists—and all the available science suggests that any such weapon would be wildly impractical. It’s possible that the symptoms of all the sufferers of Havana syndrome share a single, as yet unknown, cause; it’s also possible that multiple real health problems have been amalgamated into a single syndrome.

It’s not the first time microwaves and embassies have mixed. From 1953 to 1976, the U.S. Embassy in Moscow was bathed in high-powered microwaves coming from a nearby building. The purpose seems to have been related to espionage—activating listening devices within the embassy or interfering with American transmissions. But a 1978 study concluded that there were no adverse health effects.

Back in the United States, microwave ovens came into common use during the 1970s. Their ability to heat food by imperceptible waves created many myths. How they actually work is well understood. Some molecules, notably water, absorb microwaves and turn them into heat. That happens across the microwave and visible spectrum: Substances absorb energy of a higher frequency and turn it into heat. It’s why sunlight heats surfaces.

There’s a persistent myth that microwaves heat things from the inside out. Anyone who has heated a frozen dinner knows that this is not true. The outer part of the frozen food thaws first, because it absorbs the microwaves before they can reach the inner part. Back in the day, when I was working for the Los Alamos National Laboratory, I had to debunk the idea that microwave heating could produce oil from underground oil shale. Water and minerals between the shale and the microwave source above ground would absorb the microwaves. In the same way, if a directed microwave beam hit people’s brains, we would expect to see visible effects on the skin and flesh. None of that has accompanied Havana syndrome.

Yet the military has always hoped for death rays. Masers, microwave amplification by stimulated emission of radiation, and lasers, the same but for light, offered some of the characteristics of a death ray. Their wave structure was coherent—all the waves were lined up—and collimated into a fine beam. All that was needed was more energy. Scientists and engineers started working on these possibilities back in the 1970s, some of them alongside the laser isotope separation program where I worked. None of this research has yet resulted in usable or practical weapons.

Initially, for chemists, the extremely narrow wavelength range offered promise. The vibrations of molecules correspond to particular wavelengths of visible and infrared light. If you could irradiate a particular bond that you wanted to react, you might control chemical reactions. That was the basis for early concepts of laser isotope separation, but many other applications might be possible.

You can think of molecules as a collection of atoms attached to each other by springs that vibrate at characteristic frequencies. If you make one of those springs vibrate more than usual, the energy will quickly activate the other springs. From there, it makes the entire molecule rotate and move in space. That motion is heat.

Redistributing that energy takes place much more rapidly than do chemical reactions, so that the selectivity envisioned was not possible. But it took a decade or more in the 1970s and 1980s to prove that, and during that time, the failed idea of selectivity settled in alongside the myth that microwaves heat from the inside out. A union of the two ideas seems to be the foundation for a Havana syndrome weapon—one that would cause selective vibrations on the inside of the victim’s skulls, without leaving visible marks or burns on the outside.

If this weapon exists, knowing how it works is critical. The NAS report fails to make this connection. The references are weak, and the committee includes no experts in microwaves and their effects. The committee is made up mostly of experts in medical-related fields. Only two out of 19 seem likely to have any expertise in microwave technology, and it is not their specialty. The section of the report on microwave effects contains about a dozen references spanning 40 years and more. The older references are probably less reliable. The studies include microwave effects on cell cultures, rats, and rhesus monkeys, and only one discusses effects at all similar to Havana syndrome.

In 1961, the neuroscientist Allan H. Frey reported that pulsed microwave radiation can cause people to hear clicking and other sounds without an actual sound being produced. This is the National Academies report’s strongest connection between microwave radiation and neurological damage, and an extended explanation is given in Appendix C. There is ongoing argument, however, as to whether the Frey effect is real—and very little scientific research seems to have been done on it in the 50 years since it was discovered.

With no clear biological connection of microwaves to Havana syndrome, it’s not possible to describe a weapon that would produce that syndrome. We do not know what frequency the supposed microwaves would be or whether they are pulsed or continuous.

And we also do not know what power the source needs to have. But the power required for a microwave oven gives us a benchmark. Microwave ovens, for example, have big power requirements, as a weapon is likely to. Microwave ovens get their power from the house supply, but a portable weapon would need its own electrical supply

Typically, to independently power a microwave oven you would need a 2,200-watt gasoline-powered generator, which would weigh around 50 pounds and measure 11 by 18 by 20 inches. For a hypothetical microwave weapon, the microwave-generating part of the weapon might be another 10 pounds heavier than that and require a similar or larger volume. If batteries were used instead of a gasoline generator, something like 200 laptop computer batteries would be needed to power the weapon.

The range of such a weapon would depend on wavelength, whether the microwave frequencies are pulsed or continuous, and the waves’ collimation, along with the materials between the weapon and its target—a range that would have to be closer to tens of feet than hundreds. A gasoline-powered model could fit in a backpack carried by a strong person. Either a gas-powered or battery-powered model might fit in a van, and definitely in a building. But all of these would be difficult to use unnoticed, or to target individually.

If there is such a weapon that can cause such effects, who is using it and how? Of course, the Russians are the prime suspects. Their military also has an interest in a death ray, and they were the ones who bathed the U.S. Embassy in microwaves during the Cold War. Diplomats and intelligence employees are likely targets. But we have no evidence that the Russians have such a weapon.

Of course, such a weapon would be classified, we are told. Mark Zaid, a lawyer who represents victims, claims that the American government knows more than it is letting on.

That may be, but it would be hard to keep the development of this kind of weapon secret. The military and associated industries are often proud of their innovations. We have heard regularly over the past 40 years of the progress of fitting a laser into an airplane, and the jet suit is popular—even if it only has fuel for about 10 minutes of flight. It’s rare that the government classifies every aspect of research surrounding a classified topic. University research on the interaction of microwaves with the brain would have been sponsored and published, and the National Academies committee would have found many more than its paltry dozen references. Although the central work on laser isotope separation was classified, the ultraviolet spectrum a colleague and I measured passed classification restrictions and was published.

The evidence for microwave effects of the type categorized as Havana syndrome is exceedingly weak. No proponent of the idea has outlined how the weapon would actually work. No evidence has been offered that such a weapon has been developed by any nation. Extraordinary claims require extraordinary evidence, and no evidence has been offered to support the existence of this mystery weapon.