After Obama introduces his Afghanistan strategy to Nato members, he is expected to call for greater support on troop deployments needed to bolster his plan.
European nations have been reluctant to commit extra troops to Afghanistan in support of about 70,000 mostly Nato soldiers already stationed there.
"The United States has already said that it will deploy another 17,000 troops to the country, which was followed up by an announcement that another 4,000 US troops will be going there to train Afghan security forces," Hamish Macdonald, Al Jazeera's correspondent in Strasbourg, said.
"What we will see over the coming days is the US lobbying very hard to see European allies send more troops as well. Whether or not they will do that is another question entirely."
However, Hillary Clinton, the US secretary of state, said on Friday that Obama will not push Nato members on the numbers of troops they can deploy.
"The Nato summit is not a pledging conference," she said.
Obama's national security adviser is confident that Nato members will agree to send extra forces eventually.
General James Jones had said on Thursday: "It would be wrong to conclude that we will not get any contributions, either manpower or resources, because I think that's not going to be the case."
Jones praised efforts by Joe Biden, the US vice-president, Clinton and other US officials to consult Nato allies in advance of the introduction of Obama's Afghanistan strategy.
"I think there's a feeling that we're all in this together, and we'll wait and see exactly how far that takes us," he said.
"But having been at Nato and having been around since 2003 working on Afghanistan, I can tell you that there is a new spirit and there's a new feeling."
Nato leaders will also formally admit France back into Nato's military command structure, after a 43-year absence.
Marcin Zaborowski, a senior research fellow at the European Union Institute for Security Studies, said that Paris' return to the Nato military wing does not automatically mean it will commit more troops to its current 2,000-strong presence in Afghanistan.
"The significance of France re-joining Nato is largely symbolic, rather than practical. There are two key issues that will come up in debate. The first is that France is going back to Nato to have more of a say in the decision-making process, the implications of which are being felt by France itself," he told Al Jazeera.
"Secondly, I think that the influence in the Nato stucture is not necessarily linked to the contibution to Afghanistan. What is really important for the US is that France is back in Nato. That sends a certain signal to other nations."
Croatia and Albania will also be formally welcomed into the Nato alliance at the summit, having both joined this week.
The summit, which marks Nato's 60th anniversary, will also examine the alliance's relations with Russia, which deteriorated after Moscow’s war with Georgia in August.
The Russian government has repeatedly stressed its opposition to what it calls the creeping of Nato into what Moscow deems its traditional sphere of influence.
|Russia's war in Georgia has highlighted tensions between Nato and Moscow [AFP]
Both Georgia and Ukraine, which were members of the former Soviet Union, have in recent months signalled their intention to join Nato.
Pavel Felgenhauer, a defence analyst and columnist for the Moscow-based Novaya Gazeta newspaper, told Al Jazeera that Russia may consider helping Nato in its mission in Afghanistan if the alliance refrains from expanding towards the Russian border.
"Russia does not like Nato much but it also does not like the Taliban in Afghanistan, which is Nato's main enemy. Right now, Russia is ready to help Nato in Afghanistan but Nato will have to take into account certain interests [of Russia].
"There is a degree of tension and most of that is because of [the war in] Georgia. For Russia, Nato is not seen as a separate player but a continuation of Washington. Moscow does not want Nato to expand into the post-Soviet space and take on Georgia and Ukraine.
"Moscow wants to see a kind of working relationship. When we give our help with logistics in Afghanistan it must come in exchange for Nato not moving into our back yard."