The multi-ethnic force is meant to extend the writ of the central government beyond Kabul and replace tens of thousands of private anti-Taleban militias who helped the US to topple the hard-line regime.
The first steps to raise an estimated 70,000-strong Afghan army were initiated in mid-2002 after the toppling of the Taliban regime by the US-led forces in late 2001.
The United States, which has some 18,000 troops in Afghanistan in addition to 8,000 Nato troops, has previously said it wanted the force to be raised by 2006. Reining in powerful warlords and disarming some 100,000 militiamen are among the major challenges facing President Hamid Karzai as he attempts to extend his authority to the provinces.