"Directed" radio frequency is the most plausible explanation for mysterious symptoms experienced by diplomats stationed in US embassies in Cuba and China, a US government report said on Saturday. The symptoms appear "to be consistent with the effects of directed, pulsed radio frequency energy," said the report by the National Academies of Sciences, Engineering. Diplomats in some postings have been plagued with nausea, headache, dizziness and other unexplained symptoms. Saturday's report marks the first time Washington has officially offered an explanation, although inconclusive, on the events which effected more than 40 diplomats between 2016 and 2018.