Mysterious attacks on the health of US personnel in Havana have struck at the heart of America's spy network in Cuba, with intelligence operatives among the first and most severely affected victims, sources said.
The attacks did not emerge until US spies working under diplomatic cover reported hearing bizarre sounds and experiencing even stranger physical effects.
The attacks started within days of President Donald Trump's surprise election last November.
However, the precise timeline remains unclear, including whether intelligence officers were the first victims to experience the effects, or merely the first victims to report it.
US officials said the situation is "ongoing".
The American state department and the CIA declined to comment on whether intelligence officers had been affected.