April 29 (UPI) -- Federal agencies are investigating at least two possible incidents on U.S. soil that appear similar to mysterious "sonic attacks" that caused debilitating symptoms in dozens of U.S. diplomats in Cuba.
Defense officials briefed lawmakers on the House and Senate armed services committee about the investigation into the incidents, including one near the White House last year, CNN and NBC News reported.
A National Security Council official was sickened in an incident near the Ellipse, a lawn on the south side of the White House in November and a White House official reported a similar attack while walking her dog in a Virginia suburb near Washington, D.C., in 2019.
Both reported symptoms similar to the "Havana syndrome" that afflicted U.S. diplomats and their support staff stationed in Cuba in late 2016. Those affected reported hearing strange sounds and experiencing steady pulses of pressure in their heads while describing a range of complaints such as ear-popping, vertigo, headaches and nausea.
Director of National Intelligence Avril Haines told lawmakers that she would provide more information on the investigations after she was asked about the incidents during testimony before the Senate armed services committee Thursday.
"I completely understand that getting the information is critical for you to be able to respond to these issues and ensure that you're able to make good decisions," Haines said. "Our concern obviously with the classification is because it's either protecting sources and methods and it's critical to our national security."
Also this week, a group of nine Canadian diplomats who served in Cuba and reported symptoms accused Canada's government of withholding information about three new cases of brain injuries resulting from the alleged sonic attacks identified in 2019 and 2020, according to a letter to Canada's Foreign Affairs Minister Marc Garneau obtained by NBC News.
In the letter, the diplomats noted that Canada's government said during a January briefing "the last case of unusual health symptoms" at the Canadian Embassy in Cuba had been in 2018.
"The distortion of information misleads the public and causes significant risk to new personnel being sent to Cuba, as they are not being fully apprised of the risks to which they are exposed," the diplomats wrote.
The diplomats said that 25 Canadian diplomats have been evaluated for potential brain injury since March 2020, although it was unclear how many were ultimately diagnosed with brain injuries.
Neither Canada nor the United States has determined a cause for the mysterious illnesses or identified a suspect for the alleged attacks.
In March, the U.S. State Department appointed former Ambassador Pamela Spratlen to oversee an investigation into the incidents in Havana.