A U.S. official at a 2023 NATO conference in Lithuania exhibited symptoms of Havana syndrome, which the Pentagon linked to Russian intelligence unit 29155.

The Pentagon's investigation contradicts earlier assumptions, suggesting that Russia could be behind the attacks and that initial cases may have originated in Germany.

The National Institute of Health found no definite proof of brain injuries, pointing to preexisting conditions and environmental causes for the symptoms.

The U.S. Congress has responded by passing the Havana Act in 2021 to provide financial aid to those impacted by the syndrome.

Despite the Kremlin's dismissal of the allegations, the intelligence community continues to probe the potential use of directed energy weapons against U.S. personnel.