Footage aired for reporters showed an apparent training operation with black-masked boys - some of whom appeared to be about 10 years old - storming a house and holding guns to the heads of mock residents. Another tape showed a young boy wearing a suicide vest and posing with automatic weapons.
It's no game, reports CBS News correspondent Mark Strassmann. One recent killer in Iraq was just 11 years old.
"He went into the home of a sheikh in the Anbar province with a box of candy that blew up, killing several," said Rear Adm. Gregory Smith, a U.S. military spokesman.
U.S. and Iraqi officials said they could offer no estimate on how many children have fallen under the terror group's control. They named just a handful of attacks blamed on women or children.
CBS News terrorism analyst Paul Kurtz discussed the new Al Qaeda-related development on The Early Show. To see the interview,
The American military said some of the tapes were found in December during a U.S. raid in Khan Bani Saad, northeast of Baghdad, and said it indicated a pattern that al Qaeda in Iraq was increasingly using children for sinister means.
"Al Qaeda in Iraq wants to poison the next generation of Iraqis," Rear Adm. Smith told reporters Wednesday inside the heavily guarded Green Zone. "It is offering children as the new generation of mujahedeen," he said, using the Arabic term for holy warriors.
"We believe this video is used as propaganda to send out to recruit other boys ... and to send a broader message across Iraq to indoctrinate youth into al Qaeda," he said.
Kids have often been used as props and pawns, reports Strassmann. In one jihadi video, a boy carries a mortar round. He's 6 years old - too small to reach the mortar without a boost.
Other scenes from the Khan Bani Saad video showed masked boys forcing a man off his bicycle at gunpoint and stopping a car and kidnapping its driver along a dusty country road. At one point the boys - wearing soccer jerseys with ammunition slung across their chests - sit in a circle on the floor, chanting slogans in support of al Qaeda.
Iraqi Defense Ministry spokesman Mohammed al-Askari told reporters that militants are kidnapping more and more Iraqi children, though he could not offer details or numbers.
"This is not only to recruit them, but also to demand ransom to fund the operations of al Qaeda," al-Askari said.
Meanwhile, the U.S. military said Wednesday that its troops, along with Iraqi forces, detained 20 suspected insurgents in four days of raids across Iraq.
In other developments: