The director of the US National Security Agency has told senators that preventing the NSA from collecting metadata about citizens would undermine the agency's surveillance activities.
US Navy Admiral Michael Rogers made the remarks during his testimony before the Senate Intelligence Committee on Thursday.
Rogers said that ending the NSA’s metadata collection program would significantly reduce his agency’s “operational capabilities”.
“Right now, bulk collection gives us the ability... to generate insights as to what’s going on,” he told the committee.
Rogers said that there is “no software technique that will fully substitute for bulk collection.”
“That independent, impartial, scientifically-founded body came back and said no, under the current structure there is no real replacement,” the NSA head said, referencing a January report from the National Academy of Sciences.
The NSA is an intelligence-gathering division of the US military, and many of its operations are secret. It frequently focuses on intercepting foreign electronic or telephone communication to help US spying efforts, though it has collected domestic telephone records as part of the controversial program.
The mass collection, which began after the September 11, 2001 terrorist attacks, was revealed in June 2013 by former NSA contractor Edward Snowden.
Last year, President Barack Obama called for "concrete and substantial reforms" to rein in the NSA's sweeping surveillance powers after his administration came under intense pressure following Snowden’s revelations.
In June, Obama signed the USA Freedom Act into law, after the Senate gave its final approval for the legislation. The bill passed the US House of Representatives in May 2015.
The new law will replace the Patriot Act, the sweeping surveillance legislation passed in the days immediately after the attacks of September 11, 2001.
The law eliminates the NSA’s bulk phone-records collection program and replaces it with a program that keeps the records with phone companies but allows the government to search them with a court warrant.
The legislation will phase out the once secret NSA phone spying program over a six months period.