US Spy Chief Slams Leaks on Surveillance Program

The top U.S. spy chief has slammed the leak of top-secret documents that have shed light on how the government collects information on people's telephone records and Internet use.

In a statement late Thursday, James Clapper, the Director of National Intelligence, defended the programs as crucial to U.S. anti-terror activities, and warned their exposure threatens national security.

"The unauthorized disclosure of a top-secret U.S. court document threatens potentially long-lasting and irreversible harm to our ability to identify and respond to the many threats facing our nation," said Clapper.