Watch John Seigenthaler’s interview with Glenn Greenwald tonight on Al Jazeera America at 8 p.m. EDT/ 5 p.m. PDT and at 11 p.m. EDT/ 8 p.m. PDT. | Click here to find Al Jazeera in your area.

Journalist Glenn Greenwald, who has been at the center of controversy ever since breaking the story about the existence of the expansive National Security Agency (NSA) surveillance program, told Al Jazeera's John Seigenthaler on Wednesday that there were "many more stories to go" based on the top secret documents taken by former NSA contractor Edward Snowden.

Greenwald also insisted that despite accusations to the contrary — the Obama administration has repeatedly said that the leaks hurt U.S national security — "nobody has been injured or in any way harmed as a result of our reporting."

During the interview, Greenwald also spoke extensively about Snowden, remarking that even though Snowden's life had "unraveled" from the fallout of the NSA revelations, he was still doing "remarkably well."

"Of all the people I know in my life, the one who is most at peace and most fulfilled and probably the happiest is Edward Snowden," Greenwald told Seigenthaler. "Because he told me recently, he gets to put his head on his pillow every night knowing that he took actions in defense of this principles."

Greenwald said he continues to correspond with Snowden on a regular basis and described how Snowden, whom the United States has deemed a fugitive, is living his life in Russia under temporary asylum.

"He spends a lot of time following the debate around the world that is unfolding and the reform movements that take place," Greenwald said. "He's always been a person of the Internet, spending a lot of time indoors, online. And essentially, he continues to do that."

Greenwald, a former Guardian columnist who is now an editor at The Intercept — a news website describing itself as being committed to “fearless, adversarial journalism across a wide range of issues” — has recounted Snowden’s story and the details of the NSA’s much-chronicled massive data collections programs in a new book titled “No Place to Hide.”

Greenwald also said in his interview that despite all that has been published about the depth and scope of the NSA program, there is still much to be revealed.

"There's among the biggest stories that are left to be reported," he said.

That apparently includes one particular story that has yet to be published because, Greenwald said, it is a "very complicated story to report."

"I do think it will help to shape how this story is remembered for many years to come, because it answers some central questions about how surveillance is conducted that still aren't answered," he said, without providing further details.

Greenwald has never been shy about criticizing what he deems the complacency of U.S. media and politicians after they learned of the privacy violations involved in collecting information from the phone records and emails of Americans and foreigners. In his interview, he addressed what it was like to be called a hero and a traitor by different segments of the population.

"I think if you're going to do journalism and the kind of journalism you want to do is adversarial journalism against those in power, then you have to expect that you're going to alienate and anger lots of people. It will be controversial. If you're not prepared for that, you probably shouldn't go into journalism," he said.

The NSA revelations touched off a heated debate in the U.S. about privacy, security and whether the U.S. government was overstepping its bounds in sacrificing the former in favor of the latter. Greenwald also presented his views on government surveillance and individual companies collecting information such as emails or Web searches, stressing that there was a "huge fundamental difference."

Greenwald said that the main difference is that the government “can put you into prison,” “can take your property” and can even “kill you.” He said this is why “the Bill of Rights and the Constitution limits what the government can do, because we've always looked at government and state power as particularly and uniquely threatening."

Al Jazeera