Bring Snowden to Justice for Intel Leaks: Sen. Thune

The former U.S. intelligence contractor who says he gave classified documents about two sweeping surveillance programs to a newspaper should be prosecuted, Sen. John Thune told CNBC on Monday.

Even if information provided by 29-year-old Edward Snowden was to bring about changes in this type of intelligence gathering, he should be brought back to the U.S. and held responsible for the leaks because "we're a nation of laws," the South Dakota Republican said in a "Squawk Box."

Snowden said he worked as a contractor at the National Security Agency and the CIA, and had been a current employee of Booz Allen Hamilton, which released a statement Sunday confirming he had been a contractor with the company in Hawaii for less than three months, and promising to work with investigators.

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In an interview with The Guardian newspaper of Britain, Snowden said he fled to Hong Kong because of the Chinese territory's "strong tradition of free speech."

National Intelligence Director James Clapper confirmed on Saturday that the U.S. uses a program called PRISM to gather data left by targeted foreign citizens using the Internet outside the United States. A separate program has been used to collect the telephone records of millions of Americans to search for possible links to known terrorist targets abroad.

"The intelligence committees' members [on Capitol Hill] knew about this. Perhaps, some of the leadership, but most members of Congress, were not aware of how broad this thing was," said Thune, chairman of the Senate Republican Conference. "I do think this probably suggests that we need to have additional oversight."

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President Barack Obama has said the programs were authorized by Congress and subject to strict supervision of a secret court. Clapper said they do not target U.S. citizens. Snowden claimed the programs are ripe for abuse.

Thune told CNBC the measures are being taken to protect Americans from terrorist attacks. "We don't want to undermine that," he said. "We've got to proceed carefully in terms of changes we make."

By CNBC's Matthew J. Belvedere. Follow him on Twitter @Matt_SquawkCNBC. Wire services contributed to this report.