"These are very, very challenging times," Joint Chiefs of Staff Chairman Michael Mullen said. "We could have an operation that was a great success tactically. But we kill one or two civilians and it's a strategic failure."
Inside a Camp Lejeune theatre packed with Marines Monday, Mullen tried to clarify the mission laid out last week by the president --protect population centers in Afghanistan and build the Afghan army without civilian casualties.
The U.S. is still after Al Quida terrorists, but the bigger concern is now a Taliban insurgency which is gaining steam in Afghanistan.
"We believe, and this is not just me alone, that we have about 18-24 months to turn this thing around, or it becomes a situation where we might not be able to do that," Mullen said.
One Marine asked Mullen will 100,000 troops be enough to win in Afghanistan? Honestly I do, Mullen replied.
Mullen also said he supports a date certain of July 2011 to begin drawing down troops.
"I am very supportive of the selection of that date," he said.
Some Marines liked the sound of that.
"Kind of gave me a better feeling, knowing we were pulling out in July 2011," U.S. Marine LCpl. Brandin Norfleet said.
But Mullen stressed there is no timeline to completely pull out.
"There's no deadline, there's no end date," he said. "There's no exit strategy associated with that."
The admiral said more soldiers and Marines can come home, when more Afghan forces can finally step in.