Up to 200 Americans reported possible 'Havana syndrome' symptoms: NBC News

Up to 200 Americans have reported possible directed energy attack symptoms, including new cases in Vienna that came to light last week, according to NBC News.

Biden administration officials have received a steady stream of cables from overseas posts reporting potential new cases of "Havana syndrome" symptoms, a U.S. official told the network.

Officials said there are now possible cases on every continent except Antarctica, with almost half of the possible cases involving CIA officers or their relatives. Around 60 cases involved Defense Department employees or relatives, while about 50 were tied to the State Department.

One official told the news outlet that while the phenomenon is global, there are a disproportionately large number of cases in Europe.

The most recently announced of such cases include a series among the U.S. embassy community in Vienna, which will be “vigorously” investigated by multiple American agencies, State Department spokesman Ned Price told reporters Monday.

The New Yorker was the first to report as many as two dozen cases in Austria’s capital.

Numerous current and former FBI agents and personnel have also reported symptoms while overseas, particularly in Europe and Central Asia, with several such employees hit in Vienna as far back as more than 10 years ago.

There was also a recent and previously unreported incident in Berlin that prematurely ended at least one diplomat's term in Germany, according to NBC.

Havana syndrome first appeared at the U.S. Embassy in Cuba in 2016 when American officials began to get mysteriously ill. Some needed hospital treatment for months, and others had brain injuries.

The cause of the illness is unknown, though some believe it is caused by an attack by U.S. adversaries using radio wave weapons.

A Defense Department spokesman told NBC that it is “heavily engaged on this issue as a part of the [National Security Council]-led interagency process across the federal government to address anomalous health incidents, and is fully committed to determining both the causes and source."

"The safety, health and welfare of our personnel remains a top priority for the Department,” the official added.