20 July 2011 Last updated at 08:44 ET

Q&A: Foreign forces in Afghanistan

Nato has begun the long process of handing power over to Afghan forces. Bamiyan became the first province to pass to local control in mid-July, setting in train the gradual withdrawal of foreign forces from Afghanistan. Most international troops are scheduled to leave by 2015, provided Afghan forces are ready to take over security.

Which areas are being handed to Afghan control? What is the future for Nato forces in Afghanistan?

Correspondents say that where the US leads, other Nato countries will follow. Earlier this year President Barack Obama announced that at least 68,000 US troops would remain in Afghanistan after a first tranche of 33,000 withdraw in the coming months. If all goes to plan, most US combat troops will be out by 2013.

Britain - the second largest contributor to Nato's Afghanistan operation - has more than 10,000 soldiers in the country, including special forces. It has pledged to pull back forces by 2015 - and earlier if conditions allow.

France has also announced the phased withdrawal of 4,000 soldiers serving in Afghanistan - 1,000 of them will be out by the end of the year. Germany - which provides the third largest contingent - has announced that the prospects of a withdrawal of its 5,000 troops are "firming up".

The US and Nato hope that as the withdrawal begins, a presence will, if necessary, be maintained indefinitely in the country to equip, train and support Afghan troops.

How successful has the Isaf operation been?

The BBC's Bilal Sarwary says that following President Obama's troop surge of 2010 - which brought the number of Nato personnel to 140,000 - the level of insurgent violence in the south of Afghanistan slowly began to diminish. That appears to be borne out by recent casualty figures. The I-casualties website says that by mid-June there had been 260 coalition deaths in 2011 - compared with 711 for 2010.

But our correspondent says that while gradual progress has been made in Helmand and Kandahar, parts of the north and centre - where Nato is thinner on the ground - are looking increasingly unstable. This is because of an increased Taliban presence, coupled with the growing strength of militant groups from Central Asia such as the Islamic Movement of Uzbekistan.

The situation in these areas is made all the more complicated, our correspondent says, because much of the north is controlled by warlords who frequently change allegiance and who regularly turn a blind eye to drug smuggling and other criminal activities.

What does Isaf do?

In its mission statement, Isaf says that its role is to "reduce the capability and will of the insurgency, support the growth in capacity and capability of the Afghan National Security Forces (ANSF), and facilitate improvements in governance and socio-economic development".

Isaf says that its priority, though, is to train the army and police in advance of its pull-out. At $2bn a week, the financial cost of the US military operation is a huge drain on the resources of the United States.

Why are foreign troops in Afghanistan and who commands them?

Nato troops in Afghanistan are deployed as part of Nato's International Security Assistance Force (Isaf). This force was established by the UN in December 2001 shortly after the US-led invasion of the country in the months following the attacks on New York and Washington in September of that year. Al-Qaeda, who were blamed for the attacks, had been given sanctuary by Afghanistan's then Taliban rulers.

Isaf's stated mission is to promote security and development; it is also involved in training Afghan soldiers and police.

Its activities were initially limited to Kabul, but its remit expanded to all provinces after October 2006.

Alongside it there are about 10,000 US troops based in eastern Afghanistan - on the border with Pakistan - under what was known as Operation Enduring Freedom.

Over the years these two missions have merged and are now no longer considered to be separate entities. They came together under the joint command of US Gen David Petraeus, who was replaced in July 2011 by another US general, John Allen.

Is the violence getting worse?

Civilian casualties are at their highest levels since the Taliban were toppled. The first six months of 2011 were the deadliest for Afghans since the war began in 2001, the UN says.

Most of the deaths were caused by roadside bombs and anti-government forces such as the Taliban, although 14% of deaths were due to Afghan or international forces.

Coalition military fatalities have climbed steadily since 2005, with 2010 the bloodiest year and May 2011 the bloodiest month so far for coalition troops. However, foreign military deaths overall this year are not at the levels seen in 2010.

Increasingly, remotely detonated explosive devices and snipers are being used to target foreign forces across the country.

As more soldiers have been killed on Afghan battlefields, there have been fierce political debates in the US, UK and European countries about troop commitments as support for the war declines.

Is it only foreign troops fighting the militants?

A cornerstone of Nato strategy is to boost the size and effectiveness of Afghan security forces in the hope they will eventually take over.

The army is expected to grow by 2,800 soldiers a month to reach a total of 171,600 by October 2011. It supports Nato operations alongside about the Afghan police force.

The coalition aims for the number of national police officers to reach 134,000 by October 2011.

US, British and other foreign forces are with Afghan police and troops every day.

However, the soldiers are paid more and are better trained and equipped - although the police may face similar risk of Taliban attacks.

Are foreign troops there only to fight?

Isaf officials often say that development without security is unachievable, and security without development is meaningless.

It says that its mission in Afghanistan is to bring lasting peace and stability, and while that primarily involves the use of military personnel to secure the country, it also requires reconstruction and development initiatives.

In some areas, Isaf troops are engaged more in peacekeeping and reconstruction than in fighting.

Activities can include rebuilding damaged schools and hospitals, restoring water supplies and damaged infrastructure and supporting mediation and local governance.

In order to do so, Isaf has deployed several Provincial Reconstruction Teams (PRTs) in different parts of the country.

How strong are the Taliban?

The Taliban and their allies have returned with a vengeance after their rout in December 2001, re-emerging as a fighting force and a major threat to the Afghan government.

The militants are thought to be only about 20,000 strong. Estimates of how many are battle-hardened also vary. But despite their relatively low numbers - and despite the increasing size of the foreign troop presence - the militants have steadily extended their influence and rendered vast tracts of Afghanistan insecure.

It has become increasingly clear to Nato that it cannot win militarily. Earlier this year it emerged that US officials had had direct contacts with the Taliban, who it is accepted will have a say in any future settlement.

Do Afghans support the foreign presence?

Most Afghans remain optimistic about the state of their country, repeated polls commissioned by the BBC, ABC News and German broadcaster ARD have shown.

But they have also become increasingly angry at civilians being killed by foreign forces, in air raids and other attacks. Nato concedes it must do better in this regard if it is to succeed in Afghanistan.

Civilian casualties and concerns over corruption and governance have contributed to continuing tensions between President Karzai and the West.

Where do the troops come from and where are they based?

The lion's share of the troops come from the US. The remainder are from some 50 other countries - including Canada, Australia, Poland and Turkey.

Troops are based in various parts of the country, but their efforts chiefly target the insurgency-racked south and east.