Mr Gates said Afghanistan must eventually handle its own security
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.
Mr De Hoop Scheffer called for a more "joined-up" international approach
The secretary-general also said a revised strategy was needed to reflect Nato's plan to admit new members. Croatia and Albania are set to join at a summit in April marking the alliance's 60th anniversary.
Georgian and Ukrainian hopes for Nato membership were also discussed in Krakow, despite opposition from Moscow to the prospect.
Nato has said the two countries can eventually join the alliance but Mr Gates said their membership was still far off.
Nato's relations with Moscow chilled last year when Russia fought a brief war with Georgia over the breakaway region of South Ossetia.
Also on Friday, a US military commander said Tajikistan and Uzbekistan, which border Afghanistan, had agreed that their territory could be used to transport non-military supplies to Nato troops.
Hours before the meeting began on Thursday, Kyrgyzstan said it was closing the US air base at Manas, part of a key supply route for its forces in Afghanistan.
Our defence correspondent says some believe that Kyrgyzstan's decision to close the Manas air base was due to pressure from Moscow - a way for Russia to show its continuing opposition to countries in its former sphere of influence joining Nato.