In a blow to diplomatic relations with Cuba, U.S. Secretary of State Rex Tillerson on Oct. 3 ejected 15 Cuban diplomats from the United States. The expulsion follows his withdrawal of most U.S. personnel from the embassy in Havana after 22 American diplomats and family members there suffered unexplained health problems.

Last November, some U.S. personnel in Havana began experiencing a range of symptoms, including hearing impairment, nausea, dizziness and mild cognitive impairment. The people affected first and most severely were intelligence officers, but later victims held a variety of positions in the U.S. Embassy. Several Canadian diplomats were also affected.

The United States informed the Cuban government of these incidents on Feb. 17, 2017. Four days later, Cuban President Raúl Castro met with then U.S. Charge d’Affaires Jeffrey DeLaurentis and, pledging full cooperation, invited the FBI to investigate.

So far, though, the investigation has been unable to determine the perpetrator or motive behind the mysterious attacks. Nearly a year after the first incidents, nobody even knows how the attacks were carried out. U.S. officials initially blamed some sort of sophisticated sonic weapon, but scientists have questioned whether sound waves alone could have produced the reported symptoms.

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