President Barack Obama and the leaders of Nato's 27 other member nations open a two-day summit on friday aimed at finding ways to keep the cold war alliance relevant in the 21st century with revamped roles including ballistic missile defense, anti-piracy patrols and counter-terrorism.
But the meeting is being overshadowed by the escalating war in Afghanistan, where the alliance is struggling to contain Taliban militants.
Nato officials say they expect unanimous support from the allies for Mr Obama's plans for a new, expanded missile defense system in Europe that would be based on an existing shield meant to defend military units from attack. The US already has a missile defense system based mainly in North America, and it is planning one for its European allies.
But Mr Obama will face tough questions from US allies on his exit strategy in Afghanistan. He will also meet with leaders of the european union tomorrow to defend his preference for stimulus spending at a time when many european nations are enacting economic austerity measures.
Tomorrow, the leaders are expected to endorse a plan by Gen David Petraeus, the top US and Nato commander in Afghanistan, to start handing over responsibility for security in some areas of Afghanistan to government forces in 2011. The plan is to end the alliance's combat role by 2014 if conditions on the ground allow, but to retain significant forces in the country after that to train and advise the Afghan army
and police.
"It will be a very important moment," Mr Adm Giampaolo di Paola, Nato's top military official, told The AP on friday. "The start of transition is also testimony that the alliance is succeeding in Afghanistan."
The alliance has 140,000 troops in Afghanistan, two-thirds of them Americans. The government's security forces are being built up to just over 300,000 members. Their Taliban opponents are estimated to number up to 30,000 men.
Nato's newly expanded anti-missile shield would cost euro 200 million ($ 273 million) over the next 10 years, said Nato secretary-general Anders Fogh Rasmussen, who also wants Russia to cooperate in the project. despite claims by protesters that debt-plagued europe can't afford it amid austerity cuts, alliance officials insisted the project is worth it.
"We think it's a good thing to have a missile defense system which is Nato-based," Britain's defense secretary Liam Fox told BBC radio 4's on Friday programme.