The details provided by Lieutenant General David Rodriguez, the outgoing No. 2 commander of US forces in Afghanistan, and Pentagon officials offered the most detailed look so far at how the US military intends to carry out the withdrawal ordered by Obama in June.

Facing growing political opposition to the nearly decade-old war, Obama announced plans to pull out about a third of the 100,000 US forces in Afghanistan by the end of summer 2012, a faster timetable than the military had recommended.

The first 10,000 troops will come home by the end of the year. But Obama left the details up to his commanders.

The Pentagon's small initial drawdown leaves as many as 8,400 troops to withdraw in the last few months of 2011, and Rodriguez said he expected commanders to wait until later in the fall before deciding how to thin out those forces.

Jeffrey Dressler at the Institute for the Study of War, a Washington D.C.-based think tank, said Rodriguez's announcement was within expectations, particularly given the need to keep the bulk of troops in place until the end of the year.