"It's very clear that the president has given us guidance that in July of 2011, we'll start to transition security responsibility to the Afghan national security forces," Mullen told "Early Show" co-anchor Harry Smith. "There's no determination of how long that will take… There's no specific guidance with respect to how many. It could be very few, it could be a large number."
Mullen also stressed that Mr. Obama has vowed to conduct the withdrawal "responsibly and it will be based on conditions on the ground."
The Chairman acknowledged the huge challenge facing U.S. and NATO forces in Afghanistan as they race to train and equip the Afghan national forces to take over security duties.
He told Smith that, at present, the Afghan National Army boasts about 96,000 troops, as many as 60,000 of whom are currently fighting alongside their Western allies. But he admits "very few" of them are ready to take the lead on combat operations.
Mullen said he understood the "stress and strain and pressure" that American forces are under in Afghanistan, particularly as 30,000 new troops are now slated for deployment to the country within the coming six months.
"They truly have been magnificent," he said in praise of the troops.
But, according to Mullen, America's military is up to the challenge.
"The Chief of Staff of the Army, Gen. George Casey, spoke with me a couple of days ago and said he is ready and the Army is ready to execute this strategy and manage it. We're moving slowly to a point where our troops will be home twice as long as they're deployed."
Mullen said that transition to longer stays at home than in the battle field would take longer for the Marines than the Army. Marines are to spearhead Mr. Obama's new surge in Afghanistan, with some troops expected to reach the country before Christmas.
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