Noises linked to mysterious injuries among US diplomats in Cuba were most likely caused by crickets — not microwave weapons — according to a declassified scientific review commissioned by the US State Department and obtained by BuzzFeed News.

The State Department report was written by the JASON advisory group, an elite scientific board that has reviewed US national security concerns since the Cold War. It was completed in November of 2018, two years after dozens of US diplomats in Cuba and their families reported hearing buzzing noises and then experiencing puzzling neurological injuries, including pain, vertigo, and difficulty concentrating.

Originally classified as “secret,” the report concluded that the sounds accompanying at least eight of the original 21 Havana syndrome incidents were “most likely” caused by insects. That same scientific review also judged it “highly unlikely” that microwaves or ultrasound beams — now widely proposed by US government officials to explain the injuries — were involved in the incidents. And though the report didn’t definitively conclude what caused the injuries themselves, it found that “psychogenic” mass psychology effects may have played a role.

“No plausible single source of energy (neither radio/microwaves nor sonic) can produce both the recorded audio/video signals and the reported medical effects,” the JASON report concluded. “We believe the recorded sounds are mechanical or biological in origin, rather than electronic. The most likely source is the Indies short-tailed cricket.”

The report’s findings fly in the face of a medical report commissioned by the State Department and published by a National Academies of Sciences panel last year, which found that microwaves were the “most plausible” cause of the symptoms. That panel was not provided with the JASON report as part of its assessment, the NAS told BuzzFeed News.

“We are grateful to the JASON Group for their insight, which while coming to no firm conclusions, has assisted us in our ongoing investigation of these incidents,” a State Department spokesperson told BuzzFeed News in an emailed statement. The spokesperson declined to answer questions about why the panel’s findings were never made public or provided to the NAS.