The commander of United States military forces in Afghanistan, General Stanley McChrystal, has formally submitted a request for more troops.
The Pentagon says it will put the request on hold until President Barack Obama decides what strategy to pursue in Afghanistan.
The BBC reports Mr Obama's military advisers are reported to be divided on whether to further escalate America's military commitment there.
More than 30,000 extra US troops have already been sent to Afghanistan since Mr Obama ordered reinforcements in May.
