U.S. Central Intelligence Agency (CIA) has found that most cases of the "Havana Syndrome" are not the result of hostile foreign operations, NBC News reported citing people who briefed on the matter.

Most of the cases are open to different explanations, including environmental causes, undiagnosed medical conditions or stress, New York Times reported citing CIA officials based on a comprehensive study.

Havana Syndrome is described as "a new syndrome that resembles persistent concussion," experienced mostly by U.S. overseas diplomats and spies in many countries.