HAGERSTOWN, Md. -- The father of the Army private suspected of giving classified U.S. documents to the anti-secrecy group WikiLeaks is breaking his silence to proclaim his son's innocence and object to his treatment in military custody.

PBS NewsHour aired clips Thursday from an interview Brian E. Manning, 55, gave for an upcoming episode of the network's Frontline program.

Manning didn't immediately return a call from The Associated Press to his home in Oklahoma City.

His son Bradley Manning, 23, is in pretrial confinement at the Marine Corps base in Quantico, Va. He is charged with 22 counts, including aiding the enemy, for allegedly stealing classified documents and causing them to be published on the Internet while working as an intelligence analyst in Iraq.

The charges involve the suspected distribution of thousands of confidential State Department cables and Iraq and Afghanistan war logs that have been published on the WikiLeaks website.

Brian Manning, speaking publicly for the first time about the case, said he doesn't believe the charges.

"I don't think that the amount and the volume of things and the environment he worked in, no, I don't think so," he told Frontline interviewer Martin Smith.

Brian Manning also says he is shocked by the restrictive conditions of his son's confinement. That includes being locked up alone 23 hours a day and having his clothing taken away at night. Pfc. Manning is given a suicide-proof smock to wear to bed.

"It's shocking enough that I would come out of our silence as a family and say, 'Now, then, you crossed the line. This is wrong,'" Brian Manning said.

The military maintains that Pfc. Manning's treatment complies with U.S. law and military regulations, and that it is not punitive as defense attorney David Coombs claims.

Brian Manning also said his son isn't particularly patriotic - "I don't think he follows any regime of any kind" - and that Pfc. Manning enlisted in 2007 at his father's urging.

"He needed structure in his life. He was aimless. And I was going on my own experience. When I was growing up, that was the only thing that put structure in my life was joining the Navy, and everything's been fine since then."