WASHINGTON -- A senior U.S. commander on Monday wouldn't predict when Afghanistan might take control of its own security and warned that NATO needs at least another year to recruit and train enough soldiers and police officers.

The assessment by Lt. Gen. Bill Caldwell, the head of NATO's training mission in Afghanistan, further dims U.S. hopes that the planned U.S. withdrawal next year will be significant in size.

President Barack Obama has said that troops will begin pulling out in July 2011, the size and pace of withdrawal depending on security conditions.

Defense officials, including Defense Secretary Robert Gates, have said they think next summer's pullout would be modest.

In a Pentagon briefing, Caldwell told reporters that Afghan army and police forces won't reach sufficient numbers until Oct. 31, 2011 -- three months after Obama's deadline to start U.S. withdrawals.

NATO has set the goal of creating an Afghan military and police force of 305,600 personnel -- 171,600 army and 134,000 police.

There are currently 249,500 personnel -- 134,000 army and 115,500 police.

But Caldwell predicted that desertion and injury rates are so high among Afghan forces that NATO will have to recruit and train 141,000 people to ensure it has the 56,000 additional personnel needed next fall.

Because Afghanistan still is scrambling to recruit and train its security forces, Caldwell said there was no accurate estimate on when Kabul might take control of even the more peaceful parts of the country.

Caldwell also said it is likely the U.S. and international community will have to pay for that force for some time, even after NATO troops leave.

"The U.S. has made an enduring commitment to be supportive," he said.

As was the case in Iraq, the training and equipping of Afghan security forces is considered the linchpin in the U.S. exit strategy. However, the effort has been particularly difficult in Afghanistan, where illiteracy rates are high, corruption is rampant and there is little banking infrastructure to ensure troops get paid.

Last June, Gates predicted that Afghan forces could take control of security in some areas by the end of this year. But diplomats in the U.S. and Europe since have said the first hand over might not occur until early next year.

A NATO conference in Lisbon in November would decide which areas would be handed over first.

Caldwell said that recruiting and retention has been aided by pay increases, particularly for Afghan police, as well as a "new sense of urgency" by the Afghan government to boost recruitment.

The U.S. also has sent more police and military trainers to Afghanistan, mostly fixing a severe shortfall that dominated NATO meetings last fall, Caldwell said.