WASHINGTON: The CIA has concluded that US diplomats suffering mysterious headaches and nausea in what has been dubbed “Havana Syndrome” were not targeted in a global campaign by a foreign power, reports said Wednesday.

NBC News, The New York Times and Politico cited multiple officials briefed on a CIA intelligence assessment on the incidents that first surfaced among diplomats in 2016 in the Cuban capital, in which US and Canadian officials complained of severe headaches, nausea and possible brain damage after hearing high-pitched sounds.

Since then, diplomatic and intelligence officials have reported similar experiences in countries including Australia, Austria, China, Colombia, Germany and Russia.

The reports said the CIA did not rule out foreign involvement in about two dozen cases that remain unexplained, which continue to be investigated. “In hundreds of other cases of possible symptoms, the agency has found plausible, alternate explanations,” the NBC sources told the network.