"We welcome a public debate about how best to safeguard both our national security and the privacy of our citizens," said Deputy Attorney General James Cole.
At a Senate hearing, most of the sparring between officials and Senators was about the Section 215 powers under the Patriot Act to access phone records, which has drawn opponents in both parties.
Intelligence officials again said that Patriot Act authority was an important tool in their work.
There were also questions today on how the NSA leaks happened.
"How soon will we know who screwed up?" asked Sen. Patrick Leahy (D-VT), the Chairman of the Senate Judiciary Committee, who was told the investigation into Edward Snowden's leaks should produce answers in the "weeks and months" ahead.