Clapper: Snowden caused 'profound damage'

US Director of National Intelligence James Clapper has called on Edward Snowden and his "accomplices" to return leaked National Security Agency (NSA) documents.

In a statement to the Senate intelligence committee, Mr Clapper said Mr Snowden's disclosure have caused "profound damage" to US.

"As a consequence, the nation is less safe and its people less secure," Mr Clapper argued.

"We've lost critical foreign intelligence collection sources, including some shared with us by valued partners."