I’ve spoken to some senior foreign service officers who were on the team tasked to investigate it. As of a year and a half ago, the working theory was that it was caused by a foreign power, but as part of an attempt to develop a new espionage device, and the effects were not intended.

Link: https://www.washingtonpost.com/national-security/2026/02/14/havana-syndrome-cia-norway-experiment/