As Congress increasingly scrutinizes U.S. surveillance programs, the government on Wednesday released declassified documents on the mass collection of telephone data in a rare glimpse into the world of intelligence gathering.

The U.S. Director of National Intelligence released three declassified documents that authorized and explained the bulk collection of telephone data, one of the surveillance programs revealed by former National Security Agency contractor Edward Snowden.

The declassification was made in the “interest of increased transparency,” the Office of the Director of National Intelligence said in a statement.

Much of what is contained in the documents has already been divulged in public hearings by intelligence officials as they sought to detail what was initially disclosed by Snowden.

Snowden’s release of the secret surveillance information to American and European media sparked an uproar in the United States and abroad over revelations that U.S. intelligence agencies collected data on phone calls and other communications of Americans and foreign citizens as a tool for fighting terrorism.

Intelligence officials have said the programs helped thwart terrorist attacks, but lawmakers have called for greater oversight of the vast surveillance programs, which expanded rapidly after the September 11 attacks on the United States in 2001.

Snowden’s passport has been revoked and he has been charged under the U.S. Espionage Act. He is stuck in limbo at a Moscow airport while seeking asylum in Russia, which has pledged not to hand him over to the United States.

BULK COLLECTION

The documents released on Wednesday include 2009 and 2011 reports on the National Security Agency’s “Bulk Collection Program,” carried out under the U.S. Patriot Act.

In addition, they include an April, 2013 order from the Foreign Intelligence Surveillance Court, which directed communications company Verizon to hand over data from millions of Americans’ telephone calls and described how that data should be stored and accessed.

The declassified documents were initially sent to congressional committees and included warning notes saying the information contained in them describes “some of the most sensitive foreign intelligence collection programs conducted by the United States government.”

They described programs that collected bulk dialing, routing, addressing and signaling information about telephone calls and electronic communications. They said the government collected telephone numbers and email addresses as well as the times and dates, but not the content, of the calls and email messages.

“Although the programs collect a large amount of information, the vast majority of that information is never reviewed by anyone in the government, because the information is not responsive to the limited queries that are authorized for intelligence purposes,” the 2009 report said.

The declassified documents were released as senior intelligence officials testified before a Senate Judiciary Committee.

At the hearing, the deputy director of the NSA John Inglis said “no” when asked if anyone had been fired over the sweeping programs exposed by Snowden.

“No one has offered to resign,” Inglis said. “Everyone is working hard to understand what happened.”

(Reuters)