Two U.S. diplomats have reportedly been evacuated out of Vietnam due to reported "Havana syndrome" incidents this week.
The incidents were apparently the cause of Vice President Harris's flight delay to Singapore on Tuesday.
Senior U.S. officials told NBC News that the "anomalous health incident" that Harris's office cited for the delays was, in fact, suspected cases of Havana syndrome, the mysterious illness that has primarily affected diplomats in overseas offices. It was first detected in 2016 when it affected CIA officials in Havana.
According to the officials, the diplomats reported hearing strange sounds around the time they were hit by the illness. These apparent "acoustic incidents" have been reported by diplomats in Cuba as well, though they have not been seen in all cases.
These incidents occurred at the diplomats' homes and not at the U.S. Embassy, NBC News reports, as staffers have been working from home due to the COVID-19 pandemic.
Symptoms of Havana syndrome include severe headaches, ear pain, nausea, fatigue, insomnia and sluggishness.
"Earlier this evening, the Vice President’s traveling delegation was delayed from departing Singapore because the Vice President’s office was made aware of a report of a recent possible anomalous health incident in Hanoi, Vietnam," the State Department said on Tuesday. "After careful assessment, the decision was made to continue with the Vice President’s trip."
When reached for comment by The Hill, a State Department spokesperson said the agency was "aware" of the reported incidents, though they declined to discuss the situation further.
"We take every report of an [unidentified health incident] very seriously and we are aware of reports of possible UHIs in Vietnam," the spokesperson said. "While we cannot discuss individual cases out of privacy and security concerns, as part of the Department’s efforts to improve our response protocols to the UHI, all individuals that report a UHI get the care they need to include medevacs when appropriate."
These reported instances of Havana syndrome have come out about one week after two other U.S. officials in Germany were also hit by the illness. Instances of Havana syndrome have also been reported on U.S. soil.
The exact cause of Havana syndrome is still not known. Individuals afflicted by it are usually relocated, though their symptoms sometimes persist in the new location. The National Academy of Sciences published a report last year that said the illnesses were likely a result of microwave or direct-energy attacks on U.S. personnel.
Updated 4:36 p.m.