Vice President Kamala Harris was delayed from traveling to Vietnam on Tuesday after her office was made aware of a possible case of the so-called Havana syndrome, a mysterious illness that has afflicted U.S. diplomats across the world.

A statement released by the State Department said Harris' office was made aware of "a report of a recent possible anomalous health incident," in Vietnam's capital city of Hanoi.

NBC News reported at least two U.S. diplomats will be medically evacuated from the country after people had "experienced anomalous acoustic incidents" over the weekend.

Some 200 US officials and family, including CIA officers, have been sickened by "Havana syndrome," CIA Director William Burns has said.

In visit to ASEAN, can Kamala Harris restore confidence in the alliance after Afghan debacle?

A US National Academy of Sciences panel in December found that a plausible theory is that "directed energy" beams caused the syndrome, which is so named because it first was reported by American officials based in the U.S. embassy in Cuba in 2016.

"After careful assessment, the decision was made to continue with the Vice President's trip," the US State Department said, without offering any further details.

A State Department spokesperson declined to confirm the medical evacuations out of privacy and security concerns but said they were aware of reports of possible unexplained health incidents in Vietnam.

Vice President Kamala Harris then went ahead with the trip and arrived in Hanoi after a three-hour delay in Singapore.

White House press secretary Jen Psaki said the Havana syndrome case was reported in Vietnam before Harris' departure but not confirmed. A safety assessment was done before sending Harris to the country, she said.