Sen. Ron Wyden (D-Ore.) suggested on Thursday that the National Security Agency tracked or considered tracking the cellphone location data of millions of people in the United States.
During a Senate Intelligence Committee hearing, Wyden asked NSA Director Gen. Keith Alexander whether "the NSA has ever collected — or made any plans to collect — Americans' cell site information in bulk."
As a member of the Intelligence Committee, Wyden has access to classified information about the NSA's surveillance programs.
But Wyden cut off Alexander, saying the NSA chief was not answering his question.
Wyden repeated his inquiry, emphasizing whether the NSA has "ever" collected cell site location data.
"What I don't want to do, senator, is to put out in an unclassified forum on anything that's classified here," Alexander said.
"General, if you're responding to my question by not answering it because you think that's a classified matter, that is certainly your right," Wyden said. "We will continue to explore that because I believe this is something the American people have a right to know."
Analyzing which cell towers a phone has connected to can allow law enforcement or intelligence officials to track the location of the phone's owner.
Wyden has been a long-time critic of NSA surveillance, but government secrecy has limited his ability to publicly discuss his concerns.
In a hearing in March, Wyden asked James Clapper, the director of national intelligence, whether the NSA collects any data on millions of Americans. Clapper insisted that the NSA does not — or at least does "not wittingly" — collect data in bulk.
After leaks by Edward Snowden revealed the agency collects data on all U.S. phone calls, Clapper apologized for the misleading comment.
At Thursday's hearing, Wyden accused the leaders of the intelligence agencies of building a system "that repeatedly deceived the American people."
"Time and time again, the American people were told one thing about domestic surveillance in public forums while government agencies did something else in private," Wyden said.