Pakistan's military released a video showing children going through exercises in training for their attacks.
Taliban leader Baitullah Mehsud then sold the children to other Taliban officials for $6,000 to $12,000, Pakistani military officials said.
Mehsud was killed in an apparent U.S. drone strike in August 2009.
Since then, there have been other sporadic cases.
In 2011, a 9-year-old girl who says she was kidnapped by militants in Pakistan and told to be a suicide bomber.