NATO ambassadors gave final authorisation Friday for the alliance to take command of security operations in southern Afghanistan, the organisation said in a statement.
The decision means that NATO's top military commander, US General James Jones, will probably approve a "transfer of authority" from the US-led coalition in the south to the alliance on Monday.
"This is NATO delivering on its commitment to Afghanistan," spokesman James Appathurai said in the statement.
The expansion will see the size of the NATO-led International Security Assistance Force (ISAF) double in the south, where Taliban fighters, drug runners and war lords are waging hit-and-run attacks on foreign troops.
The operation is NATO's most ambitious undertaking, eclipsing even its air campaign against Serbia in 1999 when then strongman Slobodan Milosevic tried to crush an ethnic Albanian uprising in Kosovo.
The move will bring to more than 18,000 the number of ISAF troops. NATO took charge of ISAF almost three years ago to try to extend the reach of the weak central government to distant and often hostile regions.
