U.S. security officials are investigating a pair of "Havana Syndrome" attacks that hit much closer to home than previous incidents, including one attack near the White House. Previous attacks involving the mysterious phenomenon — Havana Syndrome is characterized by inexplicable neurological symptoms and even brain damage — only targeted American personnel who were outside the U.S.

Congress recently called on defense officials to brief lawmakers about an incident on the Ellipse, a lawn area just south of the White House, that had sickened a National Security Council official, CNN reported Thursday. An attack in 2019 targeted a White House official walking her dog just outside of Washington, D.C.

Officials have been unable to pin down the vector and perpetrator of the attacks, which were first reported in 2016 by staff at the Cuban embassy. The elusive ailment is characterized by a set of symptoms including vertigo, pounding headaches, ear-popping, nausea, and sometimes a "piercing directional noise."

Some have reported more serious injuries, including a CIA agent forced to retire in 2020 after being diagnosed with a traumatic brain injury following a trip to Russia.

After the Cuban embassy was forced to dramatically downscale, reports began popping up in Russia and China. An investigation by the National Academy of Sciences found that it was most likely due to “directed pulsed RF (radio frequency) energy.”

"The mere consideration of such a scenario raises grave concerns about a world with disinhibited malevolent actors and new tools for causing harm to others, as if the U.S. government does not have its hands full already with naturally occurring threats," the investigation read.

A recent letter from Canadian diplomats accused their government of suppressing information about further cases involving Canadian personnel.

The White House lowered the US flag to half-staff to honor the victims of the shooting in Atlanta, Georgia
A White House official and an aide to House Speaker Nancy Pelosi have contracted COVID-19. Both were with the group of Texas Democrats who traveled to Washington last week. AFP / JIM WATSON

The CIA, State Department, and Department of Defense all have ongoing investigations into the incidents. The Pentagon ramped up its efforts toward the end of the Trump administration, concerned that the other agencies weren’t doing enough.

"I knew CIA and Department of State were not taking this [expletive] seriously and we wanted to shame them into it by establishing our task force," Chris Miller, a former acting Secretary of Defense, told CNN.

Miller said the investigation found a new case “every couple of weeks." Those cases went beyond targeting officials and included their children and others close to them.