US Defence Secretary Donald Rumsfeld has denied American-led coalition forces are losing the fight against insurgents in Afghanistan.
He was speaking from Afghanistan on an unannounced visit for talks with Afghan President Hamid Karzai.
The number of "terrorists" being killed meant it was hard for them to say coalition forces were losing, he said.
His visit came a day after the UK said it would send 900 extra troops to Afghanistan, amid a spate of violence.
On Tuesday, the US-led coalition said coalition and Afghan forces had killed at least 30 militants in an operation in southern Afghanistan.
A coalition helicopter made an emergency landing and had to be destroyed during the raid in Sangin on Tuesday, in the volatile Helmand province, the coalition said.
The raid was conducted as part of Operation Mountain Thrust, a large-scale anti-Taleban offensive involving more than 10,000 US-led troops.
Mr Rumsfeld's talks with Mr Karzai were designed to strengthen strategic ties and discuss issues arising from the increasing Nato role in Afghanistan.
Speaking afterwards, the US defence secretary reaffirmed his country's commitment to Afghanistan, saying the Nato presence did not mean the US was losing interest.
Mr Rumsfeld conceded that violence in Afghanistan often came from neighbouring countries.
He said Afghanistan's neighbours were helping to combat cross-border infiltration, but he said more needed to be done.
And he paid tribute to the people of Afghanistan.
"I think that just a few short years ago, what was happening in this country - with the al-Qaeda and the Taleban brutalising the Afghan people, and attacking innocent men, women and children in the United States.
"Today the terrorist training camps have been shut down, soccer stadiums are being used for soccer instead of executions, and this is certainly a tribute to the people of Afghanistan."
Karzai under strain
Hundreds of people have died in southern Afghanistan over the past few weeks and, according to the BBC's Alastair Leithead, Mr Karzai is starting to feel the strain.
The Afghan president has called for reform and a strengthening of the police and army, extra resources and equipment and better assistance for provincial government improvements.
But perhaps more importantly, our correspondent says, he has called for the international community to reassess the manner in which the war against terror is conducted.
On Monday, UK Defence Secretary Des Browne told MPs that reinforcements, which will boost UK troop levels in Afghanistan to 4,500, would head for the Helmand province to help security and reconstruction efforts.
Extra troops were requested for the region following the deaths of six British soldiers in the past month.
Speaking after the talks with Mr Rumsfeld, Mr Karzai praised the US for the assistance it had given Afghanistan, saying it had transformed his country.
"Without the United States, Afghanistan would have not been a free country today," he said.
"Without the United States, Afghanistan would have, even now, been ruled by al-Qaeda and terrorism."