The United States' top intelligence official has defended Washington's secret monitoring of Internet users, insisting the vast operation is both legal and vital to national security.
Director of National Intelligence James Clapper confirmed on June 8 that U.S. spy agencies use a system called PRISM to gather data trails left by targeted foreign citizens using the Internet outside the United States.
He told NBC News the data collection under the program was conducted with the approval of the secret Foreign Intelligence Surveillance Act Court and with the knowledge of Internet service providers.
Clapper said the National Security Agency has requested that the Justice Department open a criminal probe into leaks to the media about the program.
On June 7, President Barack Obama defended the counterterrorism methods and said Americans need to "make some choices" in balancing privacy and security.
Based on reporting by AP and Reuters