MCLEAN, Virginia - An extensive US intelligence community investigation has concluded it was “very unlikely” a foreign adversary was responsible for the “Havana syndrome” ailments that have afflicted US diplomats and intelligence officers worldwide, according to declassified findings released on Wednesday.

The mysterious ailment, first reported among US officials in the Cuban capital in 2016, has afflicted US diplomats, officials and family members overseas.

Symptoms have included migraines, nausea, memory lapses and dizziness.

The US intelligence assessment found no credible evidence that any American adversary had a weapon or device capable of causing symptoms consistent with the syndrome.

As part of the investigation, which lasted more than six years, US intelligence agencies considered the possibility that extraterrestrials were responsible for the Havana syndrome but ruled that out, a US official said, in a briefing to reporters.

In January, a CIA official said the agency found it was unlikely that Russia or another “foreign actor” caused most of the anomalous health incidents.

That official, describing the conclusions of an interim report on the Havana Syndrome, said a majority of 1,000 cases “can be reasonably explained by medical conditions or environmental and technical factors, including previously undiagnosed illnesses.” REUTERS