Director of National Intelligence James Clapper wants former NSA systems analyst Edward Snowden to return the rest of the secret documents he took before making them public.

Clapper told a Senate Intelligence Committee hearing Wednesday that Snowden’s disclosures of National Security Agency spying have caused “profound damage” by revealing surveillance methods to terrorists, who he says are changing how the communicate to avoid detection.

Snowden took a trove of documents about the NSA’s surveillance programs, revealing that the agency sweeps up millions of Americans’ phone and Internet records. The ensuing outcry has led President Barack Obama to ask agencies and Congress to consider some reforms.

(AP)