The fear of al-Qaida's resurrection on Afghan soil after the Nato troops pull out in 2014 was evident at the two-day Nato summit in Chicago.

Nato leaders nevertheless reaffirmed their commitment to withdraw troops as per the deadline. The summit declared that the decision is irreversible.

"We are now unified behind a plan to responsibly wind down the war in Afghanistan. Are there risks involved? Absoulutely," US President Barack Obama said in his concluding speech at the summit, Reuters reported.

The differences of opinion among Nato countries were also palpable about the success against the Taliban militants over the decade since the Afghan war began.

"It is unrealistic to assume that Afghanistan is going to be completely secure and there is no possibility of a terrorist threat re-emerging," Reuters quoted an unnamed senior British official as saying. But our achievements of the last decade mean that we will withdraw from a country where the threat is much reduced and where Afghan forces are now much more able to respond to that threat," the official said.

Earlier, French President Francois Hollande confirmed his country will withdraw its troops by the end of 2012, two years earlier than the scheduled departure, accordnig to a pledge he made during his election campaign.

Washington is allegedly seeking financial compensation for its early withdrawal of troops.

Reports suggest New Zealand also decided to withdraw its troops a year earlier than the actual deadline.

British troops will be gone by the end of 2014, except for a minimum force which will remain for training purposes, according to earlier reports.

All Nato leaders pledged to help Afghanistan after the troops withdraw.

"The Afghan war as we understand it is over, but our commitment to friendship and partnership with Afghanistan continues," the Telegraph quoted Obama as saying.

"There is more to be done, but we are resolved to work together to preserve the substantial progress we have made during the past decade. The nations contributing to International Security Assistance Force will therefore continue to support Afghanistan on its path towards self-reliance in security, improved governance, and economic and social development," the summit's official statement said.