Transcript for 'This Week' Game Changer: Edward Snowden
Now we turn to the hacker who made headlines around the world with the most extensive intelligence revelations in history. A secret surveillance record that went further anyone imagined. It set off alarm bells across the security. And at least one federal judge believes he uncovered a program that violates our constitution. He's been called a patriot and a traitor. A fugitive and a freedom fighter. How ed snowden will spend 2014 and the rest of his life is anybody's guess. As pierre thomas reports, his dramatic actions in 2013 will reverberate for years to come. My name is ed snowden. I'm 29 years old. Reporter: With that, the world was introduced to the mild-mannered i.T. Guy. Fracture international relationships. I had access to, you know, the full rosters of everyone working at the nsa, the entire intelligence community and uncovered assets around the world. Reporter: And he used that access to secretly steal a treasure trove of a nice's most sensitive information. He not only steal the secrets, he gave them to the press to public. To some he's a hero. To others, a traitor. I don't think mr. Snowden was a patriot. Reporter: Snowden fled the country to hong kong and is completely committed to his cause. He wants to expose what he believes massive violation of privacy in order to fight terror. This is the truth. This is what's happening. You should decide whether we need to be doing this. Reporter: His actions revealed some stunning gaps in national security. He secretly downloaded the material for months, undetected, and walked out the door. How someone at his level was able to get access. It's hard for me to fathom how this was allowed to happen the way it did. Reporter: June 5th, the first explosive leak is published in the british newspaper, "the guardian." The public had never seen anything like it, the bombshell that under court order, verizon was providing the nsa with phone records of millions of customers. Among the information, the time and calls being made. It's something the nation's top spy had publicly deny. Does the nsa collect any type of data at all on millions or hundreds of millions of americans? No, sir. It does not? Not wittingly. Reporter: It sent shock wave throughout the entire u.S. Intelligence community. Time and time again, the american people were told one thing about domestic surveillance in public forum, while government agencies did something else in private. Reporter: Just recently, a federal judge in washington stated he believes that data-gathering is unconstitutional and could violate the fourth amendment. Protecting against unreasonable searches. But snowden critics said that he's unleashed ominous consequences for the country. Putting just enough out there to be dangerous is dangerous to us and it's dangerous to our national security. Reporter: The leaks officials say have caught the attention of terrorists. Are we less safe because of what snowden took? Yes, we are. We know that already certain al qaeda elements have changed their means of communications 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. Not just defense but some of our preemtive abilities. Reporter: As for the diplomatic damage, enorms. Authorities say for hostile intelligence agencies the leaks are a bonanza. For friendly nations the revelations of spying on allies are foreign diplomatic disaster. It's the latest bombshell from edward snowden. There you see president obama looking relaxed with other world leaders at the g-8 summit, only hours after the guardian revealed that america had spied on its own allies. Reporter: Monitoring phone calls of allies, merkel. All forcing the president to engage in full-on diplomatic damage control and the damage is far from over. Should we be expecting more revelations from you? You should. Reporter: "The guardian's" editor recently testified before parliament that only a tiny part of the leaks have been revealed. It's about 1%. Only 1% of the information in those files has now gone public? Yes. Reporter: Wikileaks has supported snowden throughout. Its leader says there's no turning back. There is no stopping the publishing process at this time. Great care has been taken to make sure that mr. Snowden can't be pressured by any state to stop the publication process. I wish there was a way to prevent it. I don't know how to stop it. I continue to be concerned about the other documents he may have, that's part of the reason why we would like to have mr. Snowden in custody. Reporter: Snowden charged with espionage and theft is now a fugitive from justice. He escaped from hong kong to russia. For weeks he was stick in limbo in a moscow airport, before being granted asylum. Whether it remains unclear whether he'll face justice in the u.S., His actions may lead to sweeping changes in what the government shares about its most sensitive spy programs. In late december, a white house review panel recommended greater transparency. It's not just the facts that matter here, it's the appearance. The fact is, nsa is not reading our e-mails. And abusing its powers. The appearance is that they are and we need to end any mistrust by opening it up. Reporter: Even the president, while still critical of snowden, acknowledges the disclosures ignited a debate. It doesn't mean that we necessarily should and the values that we got as americans are ones that we have to be willing to apply beyond our borders. Reporter: And with many more potential leaks to come, the debate is far from over. For "this week," pierre thomas, abc news, washington.
This transcript has been automatically generated and may not be 100% accurate.