Defence ministers from Nato nations are meeting in Berlin with one of the key issues for debate being the deployment of its forces in Afghanistan.
The US would like to see the Nato-led mission in Afghanistan expand
The two-day meeting will review plans for Nato forces to move into areas in 2006 where US forces now operate.
Correspondents say the contentious issue is unlikely to be resolved before Sunday's election in Germany.
Modernising the defence alliance and fixing a summit date to discuss its expansion will also be on the agenda.
Afghans now have a constitution, an elected president, and, after polls this Sunday, should have an elected parliament.
But security remains a key concern, with US forces suffering their heaviest losses this year since the 2001 invasion.
Nato took over command of the International Security Assistance Force (Isaf) in Afghanistan in August 2003.
At present, the 11,000-strong peacekeeping force is concentrated in Kabul, with additional units in northern and western areas where security has been less of a problem.
The US would like to see Isaf mission expanded to take control of operations in the south and east, where the violence is greatest, by the end of 2006. This would allow the US to enact a partial withdrawal of some of its 18,000 soldiers in Afghanistan.
"Ministers are looking at options which would allow the conduct of two complementary missions to go ahead under single leadership," John Colston, Nato's secretary general for defence policy and planning, said ahead of the meeting, according to AP news agency.
But strong doubts have been expressed in European nations - notably Germany, France and Turkey - about bringing their troops into frontline combat, and correspondents say there is unlikely to be a final agreement on the plans with tightly contested German parliamentary elections coming on Sunday.
Ministers will also discuss US proposals to hold Nato summits in 2006 and 2008 - the second to look at possible enlargement, reports AP.
Nato Secretary General Jaap de Hoop Scheffer is also set to present ideas on how to continue the modernisation of the 26-member alliance, which has roots in the Cold War era, to meet modern requirements for flexible, speedy units.
Current Nato missions include training Iraqi officers in Baghdad and airlifting African peacekeepers to Sudan.