Cellphone surveillance devices were detected near the White House and other sensitive locations in the Washington, DC, area last year, a government study found.
The spying technology, called International Mobile Subscriber Identity devices and known alternatively as Stingrays or IMSI catchers, was discovered as part of a review by the Department of Homeland Security conducted last year and detailed in a letter the agency sent to Sen. Ron Wyden, D-Oregon, last month.
While the presence of the technology in the nation's capital had been previously reported, its presence near the White House first emerged in the May letter after elected officials pressed DHS for more information amid concerns about the potential national security threat posed by the devices and vulnerabilities in the nation's telecommunications network.
Writing to Wyden in May, DHS's acting National Protection and Programs Directorate head Christopher Krebs said the department had not determined which groups were behind the surveillance activity and raised the possibility that the signals detected could have come from legitimate sources.
"It is my understanding that relevant law enforcement and counterintelligence agencies conducted further investigation and determined some detected signals were emanating from legitimate cell towers," Krebs said.
ISMI devices act essentially as fake cell phone towers and, as mobile devices connect to them, they are able to snoop on the traffic that goes through. Their legal use in the US is limited to official law enforcement and public safety entities, but the technology poses significant benefit for foreign espionage.
In a statement Friday, Wyden demanded telephone companies and the Federal Communications Commission act to curtail the potential targeting.
"The news of a possible foreign stingray near the White House is of particular concern giving reports that the President isn't even using a secure phone to protect his calls," Wyden said. "The cavalier attitude toward our national security appears to be coming from the top down. It is high time for the FCC and this administration to act immediately to protect American national security."