Nato defence ministers say they are confident that their decision to nearly double the number of troops in Afghanistan will curb rising violence.
Violence has risen sharply over the past month
The alliance has approved plans that will see the number of troops increase from 9,000 to about 17,000.
Nato says it will also expand into the insurgent-troubled south by late July.
In the latest violence, three members of the Afghan national army were killed by a roadside bomb in the province of Ghazni. Three others were injured.
"We are under no illusion that our future task will be easy. Challenges and dangers lie ahead," Nato Secretary-General Jaap de Hoop Scheffer told the meeting of alliance defence ministers in Brussels.
Correspondents say that alliance's increased deployment in Afghanistan could be its toughest ground combat role since its creation in 1949.
"I'll be blunt: more resources are urgently needed for reconstruction and development," said the secretary-general.
He called on the UN, the European Union, and the G-8 group of rich nations to come forward with more offers of aid.
The Brussels meeting is also being attended by the Afghan Defence Minister, Abdul Rahim Wardak, who predicted that "increased prosperity and security... will marginalise the extremists".
However, correspondents say the defence ministers are concerned that rising casualties among Nato troops in Afghanistan could create public opposition in their home countries.
In the latest violence, Afghan army officials say a roadside bomb in the province of Ghazni killed three soldiers and wounded three others.
They say that the explosion happened 10 kms (5.5 miles) south-east of the town of Ghazni on Thursday morning.
Eyewitnesses say that the bomb completely destroyed the vehicle that the soldiers were travelling in.
The army said the attack was the work of "enemies of Afghanistan", a phrase used to the denote the Taleban.
Correspondents say that the Taleban and their allies have increasingly used roadside bombs against the US-led coalition in Afghanistan.
A roadside bomb is also reported to have wounded four US-led coalition soldiers when it blew up near their vehicle in southern Afghanistan, a spokesman for the force said on Thursday.
He said that the attack occurred on Wednesday in Zabul province, about 300 kms (185 miles) south of the capital Kabul.
The US military said earlier this week that two US soldiers were killed in a bomb attack in eastern Afghanistan on Tuesday.