Lt. Col. Ralph Peters (U.S. Army, Ret.) blasted Hillary Clinton on Friday over her use of a private email server and the revelation that some of her emails dealt with classified drone strikes.

While appearing on Fox Business Network, Peters commented on the sensitivity of the operations involved and how dangerous her use of the private server was.

"The thing that struck me is these emails were about drone strikes before they happened," co-host David Asman said. "If somebody had gotten into that private server of hers, through which these emails traveled, somebody would have had information about a strike before it happened, right?"

"Oh, absolutely. And as a former intelligence officer, I can guarantee you people were in her private server," Peters said. "One of the things the Wall Street Journal article featured was a Clinton supporter saying, ‘there's no evidence that anybody was reading her emails.’ Good intelligence agencies don't leave footprints. You don't know they're reading your stuff."

Peters said that Clinton knew what she was doing at the time.

"But you said these are very classified operations. That would mean to me, that the emails were very classified. Should not the secretary of state had known that she was putting classified emails up in her private server?" Asman asked.

"She knew. There's no question about it," Peters said.

"There's no question in your mind?" Asman asked.

"None. None whatsoever," Peters said.

"Because she has said categorically, they were not only not labeled classified, but I would have known if they were classified," Asman said.

"Well, it's certainly true she would have known and she did know," Peters said. "They weren't labeled classified, any of these messages, because she made it a point not to put labels on them."

Asman later asked Peters to compare David Petraeus' email controversy with Clinton's.

"David Petraeus stole a candy bar. Hillary Clinton robbed Fort Knox," Peters said.