Taliban-led rebels have been hit so hard recently that they are being forced to recruit children and their command structure has been fractured, a U.S. commander said Saturday, despite a recent surge in violence.

Despite the setback — more than 500 rebels have been killed since March — militants are likely to step up attacks in the lead-up to crucial Sept. 18 legislative elections, Maj. Gen. Jason Kamiya (search) told The Associated Press in an interview.

"The Taliban (search) and Al Qaeda (search) feel that this is their final chance to impede Afghanistan's progress to ... becoming a nation," said Kamiya, the U.S. military operational commander in Afghanistan. "They will challenge us all the way through Sept. 18."

But he said the ranks of Taliban in some areas have been so devastated by heavy fighting that the rebels are forcing families "to give up one son to fight."

"They have been hit so hard they now have to recruit more fighters. They are recruiting younger and younger fighters: 14, 15 and 16 years-old," Kamiya said. "The enemy is having a hard time keeping its recruit rates up."

He said part of the reason the rebels have suffered such unprecedented losses recently was that they have been caught gathering in large groups three times and pounded by airstrikes and ground forces. Some 170 suspected insurgents were killed in a weeklong battle in June in a mountainous militant hide-out.

"There is no (rebel) organizational chain of command ... because we have succeeded thus far in disrupting their means to regroup and conduct a coordinated attack," Kamiya said. "They can no longer move around with impunity."

His comments came despite Afghanistan's government warning that the Taliban and Al Qaeda have launched a campaign to subvert the elections — the next step toward democracy after a quarter century of fighting.

Last month, militants in Kunar province, near the border with Pakistan, ambushed a U.S. Navy SEAL team (search) killing three commandos, and hours later shot down a special forces helicopter with 16 troops on board. It was the deadliest loss for U.S. forces in Afghanistan since ousting the Taliban in 2001.

Hundreds of Afghans also have been killed in recent months in near-daily ambushes, bombings and execution-style killings. The increase in violence has prompted local politicians and international observers to caution that three years of progress toward peace was threatened.

Kamiya's warning that children are being recruited into the Taliban comes two days after the United Nations said that most of an estimated 8,000 child soldiers in Afghanistan would have been demobilized and enrolled in education programs by the end of this year.

But the program has focused largely on areas beside the country's southern and eastern regions, where the Taliban are strongest.