Intelligence agencies investigating mysterious suspected sonic attacks on US diplomats in Cuba and China believe that Russia is the main suspect, officials told NBC news on Tuesday.
NBC, citing three US officials and two others briefed on the investigation, said the suspicions were backed up by evidence from communications intercepts during the investigations by the FBI, the CIA, and other US agencies.
The officials declined to elaborate on the nature of the intelligence, NBC said, adding that the proof was still not conclusive enough to directly confront Russia.
US diplomats and staff at the consulate in the southern Chinese city of Guangzhou recently fell ill after hearing strange sounds, with several evacuated to the US and at least one diagnosed with brain trauma.
The cases eerily echo the odd noises and subsequent illnesses suffered by 24 US diplomats evacuated from Cuba since 2016, deepening a baffling medical enigma.
Washington expelled 15 Cuban diplomats, arguing the authoritarian state must have either carried out the assaults or known who was behind them. US President Donald Trump said he held Cuba responsible, although Havana denied any involvement.
Last week State Department officials said the incidents should be considered “attacks.”
“The State Department has come to the determination that they were attacks,” Ambassador Peter Boode, who leads the task force responding to the incidents, told a House Foreign Affairs Committee panel, according to NBC.
However, for others it is not so clear.
Although the American victims heard strange noises — described as static or the sound of metal sheets waving — studies have cast doubt on the “acoustic weapon” hypothesis.
A University of Pennsylvania team examined 21 affected staff from the Cuba embassy, and found they suffered symptoms typical of concussion such as headaches and memory loss.
“There is no known mechanism for audible sound to injure the brain,” said study author Douglas Smith. “We are pretty certain that it was not the sound itself that caused the injury.”
A Canadian investigation into similar illnesses among its own diplomats in Cuba in April said a sonic attack was “now considered unlikely,” while FBI agents sent to Havana reportedly found no evidence to support the theory.
This has not stopped speculation about other possible weapons potentially using microwaves, infrasound, or ultrasound, despite technical difficulties in projecting these types of energy over long distances and through structures.
NBC said the US was trying to reverse engineer the suspected weapon at Kirtland Air Force Base in New Mexico, where the military has giant lasers and advanced laboratories to test high-power electromagnetic weapons, including microwaves.
A University of Michigan study in March posed an alternative theory, suggesting the illnesses could be caused by bugging or surveillance jamming devices.
The study showed ultrasonic signals from such devices could clash with each other to create the strange sounds heard by diplomats.
Importantly, this theory would suggest there was no malicious intent — and even that the US’s own equipment could be the cause.