Vice President Harris' trip from Singapore to Vietnam was delayed by more than three hours Tuesday after her staff was made aware of "a recent possible anomalous health incident" in Hanoi, according to a statement from the U.S. Embassy in Vietnam.
The "anomalous health incident" — which is how the U.S. State Department refers to mysterious symptoms that have affected dozens of Americans working in embassies and consulates across the world — affected embassy staff in Vietnam but not anyone from the vice president's staff.
U.S. officials still don't know what causes these symptoms, usually referred to as "Havana Syndrome," but there are theories they involve targeted microwave or sonic attacks. Havana Syndrome has affected more than 200 U.S. officials and their family members around the world in countries such as Cuba and China.
NBC News reported that at least two U.S. personnel in Hanoi will be medevaced out of country after Havana Syndrome incidents over the weekend. NPR has not independently confirmed this reporting.
The embassy statement said that "after careful assessment" the decision was made for the vice president to continue on.
Harris is in Southeast Asia for a weeklong visit, her second international trip while in office, to help the administration rebuild relationships with allies in the region as China expands its influence.