Conditions must be right before any pull-out, says Nato chief
Nato is preparing to hand control of parts of Afghanistan to the Afghan people this year, Secretary General Anders Fogh Rasmussen has said.
Nato foreign ministers, and their partners in the international coalition in Afghanistan, have been meeting in the Estonian capital Tallinn.
They endorsed a plan to gradually transfer security and governance powers to Afghan authorities.
The US and Nato have 126,000 troops there, rising to 150,000 by August.
US President Barack Obama has said that the US aims to begin pulling troops out of Afghanistan in 2011.
But at the heart of Nato's strategy is creating the right conditions to allow the Afghan government to take full control.
"As of today, we have a road map which will lead towards transition to Afghan lead [control], starting this year," Mr Rasmussen said.
Nato says it now has a road map leading to transition
"We agreed the approach we will take to transition. We set out a process, the conditions that will have to be met, and what we will do to make those conditions happen."
Mr Rasmussen said that the transition must not only be "sustainable but irreversible".
The BBC's Nick Childs - who is at the meeting in Estonia - says that Nato does not like talking about withdrawal or exit strategies for Afghanistan, especially when there are still key concerns about the relationship with the Afghan government and the performance of Afghan forces.
Western allies have long seen a self-sufficient Afghan armed forces, with some support from Nato, as the key to ensuring Afghanistan's long-term stability.
Mr Rasmussen said earlier this week that 450 military and police trainers were still needed to help build up the Afghan security forces.
He said he hoped that the Afghan government and other donor countries would endorse the plan at a conference to be held in the Afghan capital, Kabul, in mid-July.
The framework for security and development would also need to be approved by Afghan President Hamid Karzai.
Nato holds its next summit in November and officials say they hope the process could be launched by then.
The coalition is currently engaged in an operation to drive the Taliban out of strongholds in the south of the country.
In the latest fighting, two US soldiers and five Taliban insurgents were killed in a gun battle in Logar province near Kabul, Nato officials say.
They say that a Taliban commander was also killed in the fighting, which took place on Thursday night.
A Nato statement said that the fighting began during a joint military search operation in the Puli Alam district, following intelligence reports that "insurgent activity" was taking place there.
"As the combined force approached the compound they began receiving hostile fire from different points, including heavy machine gun fire," the statement said.
It said that a search of the compound later unearthed automatic rifles and material for making roadside bombs.
The latest deaths bring the total of foreign troops killed in Afghanistan this year to 168, according to the icasualties.org website.