New revelations from former security contractor Edward Snowden that US intelligence agencies have access to a vast online tracking tool came to light on Wednesday, as lawmakers put the secret surveillance programs under greater scrutiny.
The Guardian, citing documents from Snowden, published National Security Agency training materials for the XKeyscore program, which the British newspaper described as the NSA's widest-reaching system that covers "nearly everything a typical user does on the Internet."
Intelligence analysts can conduct surveillance through XKeyscore by filling in an on-screen form giving only a "broad justification" for the search and no review by a court or NSA staff, the newspaper said.
Snowden's disclosures to media that US intelligence agencies collected data on phone calls and other communications of Americans and foreign citizens as a tool to fight terrorism have sparked uproar in the United States and abroad.
Intelligence officials insist the programs helped thwart terrorist attacks and saved many American lives.
"The implication that NSA's collection is arbitrary and unconstrained is false," the agency said in a statement in response to the Guardian's new report, calling XKeyscore part of "NSA's lawful foreign signals intelligence collection system."
Opposition to the sweeping surveillance programs has been gaining traction in Congress, despite intense lobbying on the intelligence agencies' behalf from the Obama administration, congressional leaders and members of the House of Representatives and Senate Intelligence Committees.
Intelligence officials were grilled at a US Senate Judiciary Committee hearing on Wednesday about their data gathering, the lack of transparency and security lapses that let Snowden get away with so much information.
SENATE, HOUSE LEGISLATION
Two Democratic members of the committee, Senators Al Franken and Richard Blumenthal, said they would introduce legislation on Thursday to force the Obama administration to provide more information about the data collection programs, including how many Americans' records were reviewed by federal agents.
"The government has to give proper weight to both keeping America safe from terrorists and protecting Americans' privacy," Franken said.
Senior intelligence officials at the hearing said they were open to making some changes in the system.
Last week, the House defeated by a narrow 217-205 margin a bill that would have cut funding of the NSA program that collects the phone records. Strong support for the measure - bolstered by an unlikely alliance of liberal Democrats and libertarian Republicans - surprised many congressional observers.
Snowden, who has been charged under the US Espionage Act and had his passport revoked, left Hong Kong more than a month ago and is stuck in limbo at a Moscow airport while seeking asylum in Russia, which has refused to extradite him.