The US defence secretary has said the ousted Taleban will never be allowed to return to power in Afghanistan and pledged continuing American support.
Rumsfeld met Afghanistan's president and its top warlords
Donald Rumsfeld was speaking after talks with warlords in the north and President Hamid Karzai in Kabul.
"Those who have been defeated... would like to come back... but they will not have that opportunity," he said.
In Brussels, US State Secretary Colin Powell said Afghanistan was now the focus for Nato peacekeeping operations.
Mr Rumsfeld said US troops would continue to play an important role in Afghanistan even if Washington's European partners in Nato increased their contribution.
Late on Thursday, there were reports of a loud blast near the US embassy in Kabul, but no reports of injuries as security forces searched the scene.
Earlier in the day, suspected Taleban militants ambushed trucks carrying government census workers, killing one and wounding 11.
In May, Mr Rumsfeld declared the end of major combat operations and a shift to the reconstruction phase.
But in recent months there have been frequent attacks on coalition troops, Afghan and foreign aid workers, Afghan officials and troops - and a number of bombings in the south.
After his talks with Mr Rumsfeld, President Karzai also pledged that the Taleban and other militants would not be allowed to disrupt Afghanistan's move towards elections next year.
Speaking after a meeting of Nato foreign ministers, Mr Powell said that he and his European allies had agreed that Afghanistan was a greater immediate priority than Iraq for peacekeeping.
"Our principal focus right now has to be Afghanistan," he said.
NATO TROOPS IN AFGHANISTAN
US-led combat force of more than 11,500, deployed across country as required
European-led peacekeeping force (Isaf) of 5,700, currently confined to the capital Kabul
European troops currently make up the 5,700-strong International Security Assistance Force (Isaf) which is charged with peacekeeping in Kabul.
Isaf operates in parallel with a US-led coalition force of at least 11,500 foreign troops who are largely engaged in pursuing remnants of the Taleban regime and their al-Qaeda allies across Afghanistan.
On Thursday, Nato's secretary-general, Lord Robertson, announced that Nato states had pledged military equipment to fill important gaps in the Isaf force including Dutch and Turkish helicopters.
The United Nations would like Isaf to expand its operations to other Afghan cities - something Nato has broadly accepted.
In the northern city of Mazar-e-Sharif, Mr Rumsfeld met two of Afghanistan's most powerful warlords, General Dostum and General Atta.
The area has seen some of the worst factional violence since the fall of the Taleban but the two men recently signed a truce and have started handing over their heavy weapons to Afghan Government control.
"They have already begun walking down that path and we certainly acknowledge that and encouraged it," said the US defence secretary.
He commended the work of the British-led Provincial Reconstruction Team (PRT) - a small team of military and civilian officers deployed in the north to help stabilise the situation.
The United States and other foreign governments are planning to increase the number of PRTs across Afghanistan from their current six to about 12.
Mr Rumsfeld said he was hoping that Nato peacekeepers based in Kabul would expand outside the capital eventually - a demand that has repeatedly been made by the Afghan Government, as well as the United Nations.
"No matter what the role Nato might take, the greater the US would take - we're a part of Nato and we'd be involved in that role," the defence secretary said.