Updated

Secretary of State Rex Tillerson says that U.S. diplomats in Havana have been the victims of "health attacks" that left them with hearing loss — the most definitive U.S. statement yet on a series of mysterious incidents that have longtime observers puzzled.

In the fall of 2016, a series of U.S. diplomats began suffering unexplained losses of hearing, according to officials with knowledge of the case. Some of the diplomats' symptoms were so severe they were forced to cancel their tours early and return to the United States, officials said. The State Department said Wednesday that there had been "incidents which have caused a variety of physical symptoms."

Tillerson said Friday that "we hold the Cuban authorities responsible for finding out who is carrying out these health attacks."