Transcript for Chelsea Manning explains why she leaked secret military documents
Back now for that ABC exclusive with Chelsea manning, the transgendered former army soldier who spent years in prison for leaking classified military secrets to wikileaks and sat down with juju Chang for her first interview. For the past seven years only a handful of visitors have been allowed to see Chelsea manning or hear her voice and yet she's become a beacon for anti-secrecy rights and transgender rights, a hero to many. But critics say she betrayed her country plain and simple. She would argue in the fog of war, it's much more complicated than that. So many people call you a traitor. Many call you a hero. Right. Who is Chelsea manning? So, I'm just me. It's as simple as that. Reporter: Yet the story she's sharing this morning for the first time is far more complex. The world first heard about her as Bradley manning in 2010 when the army intelligence analyst was charged with leaking the largest trove of government secrets in U.S. History. Do you feel as though you owe the American public an apology. I've accepted responsibility. No one told me to do this. Nobody directed me to do this. This is me. It's on me. Reporter: It was images like in that manning says compelled her to go to wikileaks. American soldiers carrying out an aerial attack on what ended being unarmed civilians including children, among the dead two reuters journalists. Oh, yeah, look at that, right through the windshield. Ha, ha. Getting all this information, death, destruction, mayhem and eventually you stop -- I stopped seeing just statistics and information and I started seeing people. Counter insurgency warfare is not a simple thing. It's not as simple as good guys versus bad guys. It is a mess. Reporter: She leaked over 700,000 documents in total saying she wanted to spark public debate. So you didn't think any of it was going to threaten national security? No. There are those who say you may have been motivated to get the information into the public's sphere but you might have given it to our enemy. Right, but I have a responsibility to the public, you know, it's not just about -- we all have responsibility. Reporter: Manning was acquitted of the most serious charge of aiding the enemy. But pled guilty to others and was sentenced to the longest prison term for any American leaker, 35 years. Within days she made another life-changing decision. What made you decide to come out as trans after being sentenced? I had to be who I am. Reporter: But the military denied her request for hormones, fighting for her right to transition so daunting she says she tried to commit suicide twice which led to time in solitary confinement. Why was it so important to you to fight for hormone treatments while you were behind bars. It keeps me from feeling like I'm in the wrong body and like -- I get these horrible -- used to get niece horrible feelings like I want to rip my body apart. Reporter: The army ultimately granted her request and five months ago after seven years in prison a gift from a parting president. Clemency. I feel very comfortable that just cyst has been served. Reporter: You haven't spoken to president Obama. What would you say to him if you could? Thank you. For giving me a chance. That's all I wanted. Wanted a chance. That's all I asked for was a chance, that's it. And this is my chance. Reporter: Even though president Obama commuted manning's sentence it was not a pardon and yet the seven years she served was already longer than any other leaker in U.S. History. But her fight is not over. She is appealing her case with lawyers from the aclu and support from amnesty international who object to her months in solitary confinement saying she has more than paid. That's the point president Obama made. You did a lot of interviews and the intelligence community is still upset. Absolutely and the portrait that emerges is a very complex character. She is a millennial who likes fashion. She has hundreds of thousands of fans on social media but she has those detractors in the intelligence community who say the bottom line even if she was trying to expose wrongdoing she should have gone up the chain of command because there's no way of knowing the long-term impact of those leaks. What did she say about the seven years behind bars, what it was really like for her. I think she said before she got hormone treatment it was despair. She attempted suicide twice because she was fighting for hormone treatments for her right to transition, her right to exist, she said but once that happened she started getting all sorts of support. Hundreds of letters every week from trans children she said often, people who would write the letter, put on the stamp and started getting flooded with social media messages and wrote an op-ed for "The guardian". What will she do now. She'll take her time. One of the wisest things, I keep pressing which issues will you be the poster child for. She said, I'm going to take a deep breath and try to figure it out. You can see all of it with Chelsea manning. It'll air next week on a special edition of "Nightline," declassify the Chelsea manning story.
This transcript has been automatically generated and may not be 100% accurate.