The US is seeking to boost international forces in Afghanistan
Nato Secretary General Jaap de Hoop Scheffer has said that failure in Afghanistan is "not an option" but he ruled out a military solution alone.
Speaking at a meeting of Nato and partner defence ministers in Krakow, Poland, he said: "We cannot afford the price of failure."
But the military effort should go hand-in-hand with reconstruction and redevelopment work, he argued.
"We should not be under any illusion there is a military solution," he said.
US Defense Secretary Robert Gates has meanwhile said America will consider paying more rent to continue using a strategic air base in Kyrgyzstan which is key to its Afghan operations.
News that the Kyrgyz parliament has voted to close the US base at Manas has overshadowed the talks in Krakow, which Mr Gates is attending.
Concerned about a resurgence of the Taleban in Afghanistan, the US said this week it would send an additional 17,000 troops to the country and would ask Nato to provide more troops ahead of a general election in August.
'Not an island'
"We cannot afford the price of failure in Afghanistan," said Mr Scheffer.
Mr Scheffer called for a more "joined-up" international approach
"Instability in an already highly unstable region, a safe haven for international terrorism and massive suffering for the Afghan people is simply too much to accept."
Mr Scheffer said the countries contributing to Isaf (the International Security Assistance Force in Afghanistan) needed to work together much more closely.
"We, the Isaf nations, must provide more forces, more trainers and an action support in a more joined-up approach," he told reporters.
"We need a regional approach because Afghanistan is not an island. We need a greater civilian effort, married up more effectively with our military operations if we are not to waste precious time and resources.
"And we need a stronger communications effort to show the good we are doing and the heinous crimes the extremists are committing."
Mr Gates said the Manas base was not irreplaceable. The Pentagon would consider "a somewhat larger payment but we're not going to be ridiculous about it", he added.
Earlier, he said the new US administration was prepared to make additional commitments to Afghanistan but expected other allies to do more too.
The 17,000 increase will bring the number of US forces in Afghanistan to more than 50,000.
The US has already deployed about 24,900 troops to serve with Isaf plus about 17,000 under sole US command.
However, there is a growing realisation in the US and the UK that allies such as Germany, France and Italy are unlikely to offer significant numbers of extra combat forces, or change the nature of their missions, says the BBC's Caroline Wyatt in Krakow.
But those countries unwilling or unable to send more combat troops will also be pushed for extra help and funding on the civil side, focussing on governance, police training and the fight against drugs, our correspondent says.
On a visit to Canada, which is due to withdraw its 2,800 combat troops from Afghanistan by 2011, US President Barack Obama said he had not pressed Prime Minister Stephen Harper for an extension of the Canadian combat mission.
Missile shield unresolved
On a separate issue, Mr Gates said the new Obama administration had not decided what to do about a proposed Europe-based missile shield to which Russia objects.
Washington needed a little time to look at the plan laid out by former President George W Bush to place missile interceptors and radar in Poland and the Czech Republic as protection against a possible strike from Iran, he was quoted as saying by the Associated Press.
Russian Foreign Minister Sergei Lavrov said on Thursday that Moscow hoped the new US administration would take a "more realistic" approach to arms control talks.
Such an approach would "correspond to the interests of strategic stability from the point of view of the international community's security", he said in Moscow.