THOMAS: The leaks sent shock waves throughout the entire U.S. intelligence community.
UNIDENTIFIED MALE: Time and time again, the American people were told one thing about domestic surveillance in public forums while government agencies did something else in private.
THOMAS: Just recently, a federal judge in Washington stated that he believes the data gathering is unconstitutional and could violate the Fourth Amendment protecting against unreasonable searches.
But Snowden's critics say he's unleashed potentially ominous consequences for the country.
UNIDENTIFIED MALE: Taking a very sensitive classified program that targets foreign persons on foreign lands and putting just enough out there to be dangerous is dangerous to us. It's dangerous to our national security.
THOMAS: The leaks, officials say, have caught the attention of terrorists.
(on camera): Are we less safe because of what Snowden took?
KING: Yes, we are. We know that already that certain al Qaeda elements have changed their means of communication based upon what Snowden has disclosed. What Snowden has done has unraveled a significant part of the defenses that we had set up after September 11th, and not just defense, but also some of our preemptive abilities to stop something before it happens.
THOMAS (voice-over): As for the diplomatic damage, enormous. Authorities say for hostile intelligence agencies, the leaks are a bonanza. For friendly nations, the revelations of spying on allies are, as one intelligence official put it, "a foreign diplomatic disaster."
STEPHANOPOULOS: It's the latest bombshell from Edward Snowden. There you see President Obama looking relaxed with other world leaders at the G8 summit today, only after hours "The Guardian" revealed that America had spied on its own allies.
THOMAS: Embarrassing disclosures that the U.S. was monitoring the phone calls of 35 foreign leaders, close allies among them, including German Prime Minister Angela Merkel.
The leaders demanded answers, with the European Union even sending a fact-finding delegation to Washington.
In protest, Brazil's prime minister canceled a visit, foregoing the pageantry of a state dinner, all forcing the president to engage in full-on diplomatic damage control. And the damage is far from over.
STEPHANOPOULOS: Should we be expecting more revelations from you?
UNIDENTIFIED MALE: You should.
THOMAS: "The Guardian's" editor recently testified before parliament that only a tiny fraction of the leaked files have been revealed.
UNIDENTIFIED MALE: It's about 1 percent of what we were given.
UNIDENTIFIED MALE: Only 1 percent of the information in those files has now gone public?
UNIDENTIFIED MALE: Yes.
THOMAS: WikiLeaks, the whistleblower organization which has leaked some of the most explosive secrets of the U.S. government, has supported Snowden throughout. Its leader says there's no turning back.
JULIAN ASSANGE, FOUNDER, WIKILEAKS: Look, there is no stopping the publishing process at this staged. Great care has been taken to make sure that Mr. Snowden can't be pressured by any state to stop the publication process.
GEN. KEITH ALEXANDER, DIRECTOR, NSA: I wish there was a way to prevent it. We don't know how to stop it.
OBAMA: I continue to be concerned about the other documents that he may have. That's part of the reason why we'd like to have Mr. Snowden in custody.