Havana syndrome is a disputed medical condition reported primarily by U.S. diplomatic, intelligence, and military officials stationed in overseas locations. Reported symptoms range in severity from pain and ringing in the ears to cognitive dysfunction and were first reported by U.S. and Canadian embassy staff in Havana, Cuba, though earlier incidents may have occurred in Frankfurt, Germany. Starting in 2016 through to 2021, several hundred U.S. intelligence and military officials and their families reported having symptoms in overseas locations including China, India, Europe, Hanoi, as well as in Washington, D.C., USA.