Up to 20 Nato countries have offered to boost their civilian, military or training commitments to Afghanistan, US defence secretary Robert Gates says.
At a meeting of Nato defence ministers in Poland, he said the alliance faced a tough test in Afghanistan but he was convinced it could meet the challenge.
The US is sending an extra 17,000 troops to Afghanistan and has been pressing its allies to do more.
Afghanistan is facing a growing insurgency from Taleban militants.
Mr Gates ended the two-day meeting in Krakow in an upbeat mood, says the BBC's defence correspondent Caroline Wyatt, as he announced the offers of increased commitments.
"Over the last couple of days, 19 or 20 countries announced at one point or another in the meetings that they would be increasing their contribution, either on the civilian or the military or the training side," Mr Gates told reporters.
Some Nato members have been reluctant to contribute more troops to the mission in Afghanistan.
Several European states have caveats preventing their forces being deployed in the most dangerous areas. Some are also constrained by domestic political opposition to the Afghan war.
However, Mr Gates said there was agreement among the 26-member bloc that they must "intensify our efforts to bring security and stability to Afghanistan, and to ensure that the Afghans are capable of sustaining it themselves".
"It is, after all, their country, their fight and their future," he said.
"So I consider that a good start as we begin to look toward the summit [of Nato leaders in April]."
By then, the US is expected to have completed a major review of its policy in Afghanistan.
Nato has also been examining its own future doctrine, our correspondent says, with secretary general Jaap de Hoop Scheffer saying on Thursday that it needed a new strategic concept to include the new challenges posed by global warming, threats to the energy supply and cyber-attacks.
"The demands on Nato are greater than ever before," he warned.