Nato's chief has defended its decision to expand its mission into the whole of Afghanistan, despite not having all the soldiers it needs to do the job.
Nato will now command more than 30,000 troops in Afghanistan
Jaap de Hoop Scheffer told the BBC Nato was fighting to stop Afghanistan from returning to a "terror training camp".
He said some allies had come forward with more soldiers, but not the 2,500 wanted to bolster troops in the south.
Nato forces in the south are facing mounting casualties as they engage in fighting with a resurgent Taleban.
In further violence, an alliance soldier has been killed by an explosion in the southern province of Kandahar while on foot patrol.
Afghan police say an officer and two militants died in an attack on a checkpoint in Zabul province, also in southern Afghanistan.
'Stay the course'
The expansion, announced on Thursday, will take the alliance into eastern parts of Afghanistan.
It will also bring up to 12,000 US troops under the Nato-led International Security Assistance Force (Isaf) command, taking the total number of troops to around 32,000.
But Nato is still seeking commitments, particularly from European countries, to send an extra 2,500 soldiers.
The Nato secretary general said they had made "very good progress", but were not "completely there".
"But I know of allies who have come forward already and I know of others who might come forward in the near future."
He said that although more forces were coming, there were still requirements that would not be met.
"If you look at the fourth phase of Nato expansion you see a very substantial number of... US forces coming in," he said.
"But having said that, that is not the final argument of not filling the requirements we need for the south."
He warned it was very important for Nato to stay.
The consequences of failure would be Afghanistan's return to "a hotbed of terrorism training and the violation of human rights", he said.
"We have to stay the course and we will stay the course - and we will prevail".
Thursday's announcement came as the US military said that militant attacks near the Pakistani border had tripled in some areas.
The Afghan and Pakistani presidents accuse each other of failing to act against the militants, with Afghan leader Hamid Karzai particularly criticising Gen Pervez Musharraf's peace deal with pro-Taleban militants in the North Waziristan border area.
He says attacks have gone up and the US findings appeared to confirm this.
Mr Karzai has also suggested that Pakistan has turned a blind eye to Taleban supporters using parts of the country to train and launch attacks on Afghanistan.
Gen Musharraf has angrily rejected allegations that his ISI intelligence service aided al-Qaeda and the Taleban.