NATO members have agreed to a detailed outline for sending about 300 military instructors to Iraq.
Alliance ambassadors Friday in Brussels approved the "concept of operations" for an officers' training school in the Baghdad region.
They also agreed to have U.S. Lieutenant General David Petraeus command the operation.
Last month, NATO's top commander, General James Jones, said the alliance may eventually need to send up to 3,000 troops to Iraq to carry out its training mission.
NATO leaders agreed on the mission at a summit in Istanbul earlier this year.
Some NATO officers are already in Iraq helping train the country's security forces and offering logistical support to Polish-led peacekeepers.
France had opposed having a NATO training mission inside Iraq, but later relented. The country is among a few NATO members that will not provide troops for the mission.