Proposed February troop reduction would coincide with increase in troops sent to Afghanistan.
As his next report on troop levels nears, senior officers aren't sure they'll agree.
As officials consider sending more troops to Afghanistan, some worry about the lack of a larger plan.
Afghan and NATO officials are seeing a rise in numbers of foreign fighters in Afghanistan at the same time US officials say attacks by Al Qaeda in Iraq have sharply dropped.
The Pentagon wants more control over NATO there in light of Taliban resurgence.
Counterinsurgency efforts require US soldiers to shift from fighting to peacekeeping, but many feel ill-prepared to conduct investigations and interact with Iraqis.
Improved security has boosted optimism, but US commanders want to be assured it is "irreversible."
A key component is likely to be more troops, but the strategy must go beyond that, experts say.