The UN still plays a critical role in Afghanistan
After the fall of the Taliban in 2001, Afghanistan was a nation in tatters - in need of basic relief, reconstruction and political and civil development.
The following year the United Nations Assistance Mission for Afghanistan (Unama) was set up to promote peace and stability in the country - with a specific focus on political and humanitarian affairs.
The BBC considers some important areas of UN activity.
THE UN'S AFGHAN MISSION
The fraught process that accompanied Afghanistan's controversial presidential elections highlighted the critical role the United Nations still plays in Afghanistan eight years after Taliban rule crumbled.
The body that investigated allegations of fraud was UN-backed and the UN is reported to have spent about $300m on the elections.
Unama is at the heart of all the UN's activities in Afghanistan. It acts as an umbrella body but its major focus is on political and humanitarian affairs.
in Afghanistan must be reviewed regularly by the UN's security council.
The latest renewal of the mandate, in March 2009, made mention of Unama's role in elections, also recognising its efforts in helping improve good governance and rule of law as well as fighting corruption and delivering humanitarian assistance.
The 2008 mandate resolution also charged the agency with monitoring human rights in the country.
The UN special envoy to Afghanistan, the head of its mission there, is Norwegian diplomat Kai Eide.
Many other major UN bodies have a substantial presence in Afghanistan where they continue to work according to their specialisation.
But some parts of the country will now be off limits to aid agencies because of the deteriorating security situation over the past year.
Decades of conflict have left large parts of Afghanistan's basic infrastructure decimated.
World Food Programme (WFP)
has been operating in Afghanistan since the 1960s but the country's needs are as acute as ever.
Data from a 2007-2008 risk and vulnerability assessment showed that nearly a third of the population was unable to get enough food for an active and healthy life - and about 37% were on the borderline of food insecurity.
On average, the WFP says it will distribute food to millions, primarily in remote and "food insecure" rural areas.
In 2009 it said it hoped to be able to feed 8.8m people.
Afghanistan's health indicators are poor: it has one of the
world's highest maternal mortality rates
and life expectancy is about 42 years.
The World Health Organization (WHO) has been working in Afghanistan for decades. It says its major role is to reduce mortality, morbidity and disability and to improve health. It works closely with other partners in this respect.
It has polio eradication initiatives, a tuberculosis programme, and a basic development needs programme.
This is essentially organising local communities to be able to provide basic healthcare needs for themselves. Approximately 32 villages were taking part in 2008.
are dependent on basic security in the areas they operate - something that is not guaranteed in Afghanistan.
President Hamid Karzai has repeatedly stressed that Afghanistan is a fledgling nation.
One of the most important aspects to the UN and Unama's work in Afghanistan is in building up civil and political institutions and processes.
Unama provides support to Afghanistan at times of election but it also has a military advisory unit, a governance unit, a police advisory unit and a rule of law unit.
Ultimately the efforts of all of these bodies, apart from monitoring the overall situation, will be directed towards preventing and resolving conflicts and building capacity and know-how at basic institutions within government and society.