CNN  — 

The leaders of the Senate Intelligence Committee warned Friday that mysterious invisible attacks that have caused debilitating symptoms appear to be on the rise against US personnel.

“For nearly five years, we have been aware of reports of mysterious attacks on United States Government personnel in Havana, Cuba, and around the world. This pattern of attacking our fellow citizens serving our government appears to be increasing,” Senate Intelligence Chairman Mark Warner, a Virginia Democrat, and the panel’s top Republican, Marco Rubio of Florida, said in a statement. “The Senate Intelligence Committee intends to get to the bottom of this. We have already held fact finding hearings on these debilitating attacks, many of which result in medically confirmed cases of Traumatic Brain Injury, and will do more.”

The statement comes after reports this week about possible incidents on US soil that appear similar to the invisible attacks affecting dozens US diplomats abroad that cause symptoms known as “Havana syndrome,” including ear popping, vertigo, pounding headaches and nausea, sometimes accompanied by an unidentified “piercing directional noise.”

CNN first reported this week on a potential incident near the White House involving a National Security Council staffer that occurred in November, one of several on US soil. Federal agencies investigating the matter have not reached a clear conclusion yet on what happened, however, or who might be responsible.

Politico reported this week that the US is investigating a possible attack on US personnel in Miami last year.

The US has struggled to understand the apparent attacks since diplomatic and intelligence personnel in Cuba first began reporting alarming symptoms in 2016. There have also been reports of the attacks affecting US personnel in Russia and China, along with the potential incidents inside the US.

A March report from the National Academy of Sciences found that “directed, pulsed radiofrequency energy” was the most likely cause of the strange set of symptoms. While the report was carefully written not to overstate its findings, it offered some of the clearest public evidence to date that the incidents could be attacks, attributing the afflictions to “pulsed” or “directed” energy.

The Pentagon and CIA have separately set up task forces to address the issue, and the State Department named a senior official to lead the department’s response. CIA Director William Burns said during his confirmation hearing that he would review the evidence on the alleged attacks on CIA personnel overseas.

“As the Chairman and Vice Chairman of the Senate Select Committee on Intelligence, we welcome CIA Director Burns’ renewed focus on these attacks,” Warner and Rubio said. “Our committee will continue to work with him, and the rest of the Intelligence Community, to better understand the technology behind the weapon responsible for these attacks. We will focus on ensuring we protect our personnel and provide the medical and financial support the victims deserve. Ultimately we will identify those responsible for these attacks on American personnel and will hold them accountable.”

The House Intelligence Committee is also working on the issue, and a spokesman for House Intelligence Chairman Adam Schiff, a California Democrat, said the reported attacks affecting personnel in Havana and around the world “are of grave concern,” adding that recent intelligence authorization legislation gave the CIA director more authority to provide benefits to those injured by hostile acts.

“We have been working quietly and persistently behind closed doors on this critical issue since the first reports, and pressed Director Burns on it during the recent Worldwide Threats hearing, in both open and closed session,” the spokesperson said. “The Committee will continue to hold events and briefings on this subject and we will follow the evidence wherever it may lead and ensure anyone responsible is held to account.”