The changes are based on a plan used in Iraq by Lt. Gen. Stanley McChrystal, who will be the U.S. commander in Afghanistan if confirmed by the Senate, CNN reported Wednesday.
"We want cohesive units, fleet of foot, specializing in counterinsurgency warfare," the military official told CNN.
The new idea being considered calls for hundreds, maybe thousands, of troops to train and deploy as a battlefield unit specializing in counterinsurgency warfare, the official told CNN.
Pentagon spokesman Geoff Morrell said Defense Secretary Robert Gates, concerned about public support for the war in Afghanistan, believes "it's critically important" for U.S. and Afghan governments to make progress against the Taliban in the coming months.
Gates has said he thinks the Taliban has momentum in southern Afghanistan, Morrell said.
"People are willing to stay in the fight I believe, if they think we're making headway," Gates recently told The Wall Street Journal. "If they think we're stalemated and having our young men and women get killed, then patience is going to run out pretty fast."