A US government report said that “directed” radio frequencies are the most plausible explanation for the mysterious symptoms experienced by diplomats stationed in US embassies in Havana and elsewhere.

Symptoms appear “consistent with the effects of directed pulsed radiofrequency energy”, The report said By the National Academies of Sciences and Engineering.

In some posts, diplomats suffer from nausea, headache, dizziness and other unexplained symptoms. This is Havana Syndrome. It has long been the subject of intense speculation, given the nature of the symptoms, the location of the posts, and the US government’s silence.

Saturday’s report marks the first time Washington has formally provided an explanation, although it is inconclusive.

Secretary of State Mike Pompeo said in October that “substantial resources have been devoted to the US government” to solve the puzzle, which affected more than 40 US government employees between 2016 and 2018.

The Foreign Ministry said in June 2018 that it had brought back two diplomats from Guangzhou, China, for fear of similar symptoms.

In addition to directed radio frequencies, Saturday’s report left the door open to “the possibility of multiple factors, including psychological and social factors.”

NBC News and The New York Times published the report’s findings for the first time.

The New York Times quoted the State Department as saying: “We are happy that this report has now been released and can add to data and analysis that may help us reach a final conclusion about what happened.”