Barack Obama passed his second foreign leadership exam Saturday when NATO backed his Afghan war plan, but he still faces the likelihood that most of the combat force will wear US uniforms.

The new US president however also enhanced his own aura, drawing praise from his peers as a fresh and decisive voice, after unpicking a row threatening the unity of a major summit for the second time in three days.

This time he gave Turkey cover to drop its opposition to the next NATO boss, Anders Fogh Rasmussen, two days after intervening between China and France to forge a compromise on tax havens at the G20 London summit.

White House aides brandished a new NATO commitment of 5,000 troops and stiffened financial pledges as proof the alliance listened to Obama's challenge to commit anew to the six-year war.

But with the conflict unpopular in Europe, the new forces, most to secure Afghan elections later this year and to train the Afghan National Army, are dwarfed by the 21,000-strong US troop hikes that Obama recently announced.

"I am pleased that our NATO allies pledged their strong and unanimous support for our new strategy," Obama said after the summit.

"It was only just a week ago that we announced this new approach, but already ... we have started to match real resources to achieve our goals."

Obama traveled to the summit, part of a week-long swing through Europe and Turkey, knowing there would be no large European combat force forthcoming, so had kept expectations low.

But facing accusations he was leading America into a quagmire or his own personal "Vietnam", he needed to convince allies Afghanistan was their war too.

"I think the president can make a pretty strong case that he has made a good start," said Karen Donfried, of the German Marshall Fund of the United States, who watched from Strasbourg as the summit unfolded.

Senior US officials said privately they saw allied commitments at the NATO summit as merely a "downpayment" on a more robust NATO civilian and military effort in the war against the Taliban and Al-Qaeda.

US observers have been particularly stressing Europe's capacity to help with the civilian and development side of the mission.

They also gently argued that the fact Obama went out of his way to consult US allies on the strategy placed increased responsibility on US allies.

"We've put together a very consultative process with our allies to make sure that their views are taken into consideration as we put together the strategy," a senior US official said on condition of anonymity.

"As a result, we also then will expect that, their views having been heard, that they're in a position to match resources against the strategy."

In his debut on the world stage, Obama did not demand an immediate response from US allies for more boots on the ground or money for the war chest, but may not always be so patient.

"Barack Obama was not expecting an answer this week. But he will be looking for an answer over the coming months," said Donfried.

Political reality suggests the US commander-in-chief may have limited time to convince US allies to put more muscle into the fight.

Even Obama, who sometimes seems immune to political gravity, has a limited half life -- as does his leverage on the continent's leaders.

Europe's politicians, including Britain's Prime Minister Gordon Brown, Germany's Chancellor Angela Merkel and France's President Nicolas Sarkozy, are all constrained by domestic political clocks.

Even if they want a more robust Afghan troop presence, they may find it tough to pull off -- a fact Obama implicitly recognized when noting a leader's toughest moments come when sending troops into battle.

US and Turkish officials said the president was instrumental in convincing Turkey to drop its objections to Danish Prime Minister Rasmussen.

"I think that our President really was instrumental in bringing about this common ground and finding this common ground," said Obama's national security advisor James Jones on Air Force One.

"I think it's a very good day for the Alliance," said Jones, whose account of the event was backed up by the Turks.

Turkey had objected to Rasmussen's defence of a Danish newspaper's right in 2005 to printing satirical cartoons of the Prophet Mohammed.

It also complained Rasmussen had failed to act on Turkish requests to a Denmark-based channel accused of links to the Kurdistan Workers' Party.