Enlarge / Picture of the US embassy in Havana, taken on September 29, 2017, after the United States announced it was withdrawing more than half its personnel in response to mysterious health attacks targeting its diplomatic staff. (credit: Getty | AFP )

In late 2016, US diplomats in Cuba began reporting bizarre and alarming episodes in their homes and hotel rooms. They spoke of irritating or piercing noises—buzzes, squeals, or clicks—that seemed to come from a particular direction but weren’t always dampened when they clasped their hands to their ears. Some described feeling pressure and vibrations, too.

With the disturbances came a constellation of debilitating symptoms: dizziness, nausea, headaches, balance problems, ringing in their ears, visual disturbances, nosebleeds, difficulty concentrating and recalling words, hearing loss, and speech problems.

Since the first 2016 reports, the mysterious episodes seemed to afflict more than 50 US diplomats and their families; more than 40 in Havana and at least a dozen more at the US Consulate in Guangzhou, China. Some CIA officers working in Russia have also reported similar cases.