All members of the Nato alliance should share the "burden" of fighting the Taleban in Afghanistan, US President George W Bush has said.
The two statesmen held an open-air news briefing
Speaking at his Texas ranch with Nato Secretary General Jaap de Hoop Scheffer, Mr Bush also said Nato must transform to meet modern-day threats.
Nato commands more than 35,000 troops battling Taleban rebels in Afghanistan.
More than 4,000 people were killed last year in fighting between militants and international-led forces.
Mr Bush and Mr de Hoop Scheffer discussed US plans for a missile defence shield in Europe and progress on the future status of the UN-administered Kosovo, as well as issues in Afghanistan.
The president said he would continue to "reach out" to Russia, which strongly objects to the missile defence plan.
Moscow also objects to plans, backed by the US and Nato, to give Kosovo a path towards independence.
The president said he understood that Nato's effort in Afghanistan would require "more than military action".
"We support a long-term comprehensive strategy to help strengthen Afghanistan's democratic institutions and help create the economic opportunity that will help this young democracy survive and thrive," he said.
But he stressed that Nato members should be more prepared to commit troops to the battle in Afghanistan.
And the alliance must be prepared to transform itself to meet the modern-day defence needs of its member states, he added.
Mr de Hoop Scheffer said that every effort was being made to avoid civilian casualties as Nato forces confronted the Taleban.
He lamented recent civilian deaths because of Nato air strikes, but insisted the organisation was "not in the same moral category" as the Taleban, who Mr Bush said frequently use civilians as human shields.
"That front line should not become a fault line," Mr de Hoop Scheffer said.