Nato foreign ministers approved mission rules on Thursday for an expanded peacekeeping force in Afghanistan next year which Washington hopes will allow it to cut US troop levels there.
The agreement leaves the most dangerous counter-insurgency work in the hands of the 20,000-strong US-led coalition but gives Nato more scope to help local Afghan forces with training and other tasks such as disarming illegal armed groups.
"When the expansion takes place next year, it will mean Nato is operating in three-quarters of the territory of Afghanistan," Nato Secretary-General Jaap de Hoop Scheffer told a news conference.
Nato is looking to raise its 9,000-strong ISAF peacekeeping force to some 15,000 troops from early next year. It will spread its bases in the north and west, and the capital, Kabul, to the more volatile south, a base for many insurgents.
Britain, Canada and the Netherlands are earmarked to lead the expansion into the south but Nato still needs further troop contributions before it can go ahead early next year.
Dutch Foreign Minister Bernard Bot said he was confident his government would agree as early as Friday to send the extra Dutch troops after he received additional assurances from Nato on security conditions.
"These were very satisfactory guarantees," Bot told a news briefing of pledges from Nato allies that they would help the Dutch if they got into danger. Parliament must also approve the deployment of an extra 1,100 Dutch troops.
He also said the Netherlands had an accord with the Afghan authorities that no detainee handed over to them by ISAF would face the death penalty. The United States, which leads Operation Enduring Freedom fighting the remnants of Taleban and al Qaeda militants, has stressed any troop cuts would depend on conditions at the time and has given no figure.
Under the rules agreed by ministers, ISAF will continue to focus on peacekeeping and security while OEF will remain largely responsible for the more dangerous task of hunting insurgents.
The two operations will co-ordinate through a "dual-hatted" officer, most likely a US general, integrated into both the ISAF and OEF command chains.
De Hoop Scheffer said Nato had agreed to develop a long-term programme of support to Afghanistan as requested by President Hamid Karzai. The programme would focus on helping authorities with defence and security sector reforms, he said.