The BBC's Alastair Leithead has been spending time with British troops on the frontline in Afghanistan.
Here, he answers readers' questions about the current situation.
How do you define the differences between Afghanistan and Iraq?
Morale among UK troops remains high in Afghanistan
Kellye, La Mirada, California, USA
Afghanistan and Iraq are very different places. Where many believe Iraq is now "lost" and high hopes of democracy have dissolved into daily chaos and a virtual civil war based around sectarianism, there is much more optimism about Afghanistan.
Yes there are two main blocks - the Pashtuns and the Persian speakers, but the society is much more sophisticated than that, with many other groups and interests represented. The Nato mission is UN mandated and there is a commitment from 37 nations to help the government redevelop and stabilise the country.
There are similarities between the nature of the terrorism between the two countries - some copycat attacks, others with physical links to the Iraqi insurgency, such as the latest armour-piercing roadside bombs.
But the majority of suicide bombers in Afghanistan in the last 12 months have killed only themselves in their attacks.
The insurgency is becoming more advanced but it's a long way off Iraq, and at least the government structures are in place and are growing.
Insurgencies are very difficult to defeat, but the military presence in Afghanistan is providing a window for Afghanistan to find itself as a country and to develop a strong political system that works in its own unique set of circumstances.
My fiance is currently serving in Afghanistan. I was wondering if you would help me to understand what they are going through?
Laura Wheeler, Shepperton, UK
The conditions are tough for British forces. In the bases such as Lashkar Gah and Camp Bastion there are luxuries such as air conditioning, excellent food and good accommodation.
In the forward bases things are obviously not as comfortable. In the desert and the Helmand river valley temperatures are on average in the high 40s Celsius, the dust is like talcum powder and gets everywhere, sandstorms blow through regularly, and soldiers live on ration packs - these are good but can get monotonous after two or three months of the same food.
On the front lines fresh water is rationed and the rest tastes like swimming pool water - warm and tasting of the chlorine purification chemicals.
There are tents with air conditioning in the fixed bases, but in the most extreme places soldiers sleep under mosquito nets outside - behind sandbags for protection.
It is a difficult place to live and fight, but morale among UK troops does seem very high.
It is also dangerous, but the bases are well protected and most of the troops are not on the front lines day in, day out so their risk levels are a lot lower.
Having travelled to the worst spots, it does amaze me how relatively few people are killed and injured with so many bullets and rockets firing around. Inevitably, and tragically, it does happen though.
Have you seen any evidence that the casualties we are told the Taleban keep taking are having any impact on their ability to fight?
Desmond Martin, St Benoit du Sault, France
The Taleban clearly are taking casualties - it's difficult not to when in places like Helmand they are fighting a guerrilla war against the International Security Assistance Force, in that case British forces.
The UK's firepower is overwhelming, but the insurgents are brave, ideologically committed, if not to the jihad then to throwing the "foreigners" out.
They are incredibly resilient, know the ground well and are being resupplied by fighters crossing the border with Pakistan. All the technology is struggling to defeat the insurgency at the moment.
But progress is slowly being made - key field commanders such as Mullah Dadullah have been killed and intelligence on the organisational structures is increasing all the time.
Military commanders argue their strategies of bringing development and assistance to local people through the elders in the aftermath of big battles is helping win their support - and that is the only real way that the Taleban will be stopped.
Only when communities turn against them will a ready source of fighters dry up.
Do you think the insurgents can be beaten?
Javed, Jalalabad, Afghanistan
Beating an insurgency is difficult, but it is a lot easier if their backers withdraw support. They cannot be beaten purely militarily, which is why so much effort, and money, is being put into development, strengthening the government's ability to govern well and trying to improve the life of Afghan people.
The Taleban are given help by people in Afghanistan - many are Afghan people - but if a stronger, clearly long-term alternative is offered then they are more likely to back the government. Only then can the insurgency be beaten.
How is the central government working with local southern governments in order to create peace for the south and all of Afghanistan?
Fara A., Washington DC, USA
The Afghan government is weak in the southern parts of the country. It's a Catch 22 situation - you can't have good governance when the security situation is so bad, but good governance is vital for improving security.
Afghanistan has a centralised state apparatus, and there are gaping holes in the way money and resources are transferred to the provinces.
Corruption and mistrust are problems, but it's mainly a lack of the capacity to spend money properly and effectively. A lot of emphasis is put on the governors - appointed by the president, but as government allies they don't necessarily have the regional tribal strength or trust to make progress when dealing with the local warlords.
It's a similar problem with corruption - do you have in provincial government people from outside, who are less likely to be locally corrupt but will not see eye to eye with the truly powerful tribal elders, or do you go with someone who is tied up with the local tribes to the extent corruption could thrive under a surface of peace and stability?
The UK's Department for International Development is spending millions in Afghanistan, but has opted to put it through the government, rather than using partner non-governmental organisations.
This strengthens government as it spends, and learns to budget effectively. It is also encouraging local government through Community Development Councils (CDCs) which make decisions on prioritising development effort.
While sometimes running parallel to traditional structures, this is all contributing towards a stronger local governance.
With the recent incident of accidental fire into a civilian crowd, are regular Afghani citizens supportive of foreign troops?
Tyranny Bean, Shelbyville, Kentucky, USA
Civilian casualties are a major problem for international troops in Afghanistan. They are here to help the government and to fight insurgents, and every civilian killed creates more enemies - some of whom will be prepared to join the Taleban to avenge the death of relatives.
It's all about trust and winning the support of local people - if that is successful local people do provide information to troops.
The importance of not killing civilians cannot be overestimated, but in places where guerrilla war is going on it's difficult as the Taleban often fight from homes and built-up areas.
The Nato and US strategy of using overwhelming force, particularly big air strikes, does increase the risks, but you could never have enough ground troops to fight a different way.
I think the overriding feeling in Afghanistan is support for the presence of international troops in the country. People may complain - and some may have serious cause to do so, but they know the alternative is a return to civil war and people here are sick of the fighting.
How are the Taleban still getting supplies of arms and ammunition?
There is a lot of evidence showing that the Taleban supply route is through Pakistan and "striking at the root" is an argument the Afghan government has used when frustrations with Pakistan periodically dip to serious lows.
Pakistan's President Musharraf is under a lot of pressure domestically and so upping the ante from the international perspective is not necessarily going to help.
Carrying out air strikes or missions inside Pakistan would infuriate the radicals who are putting the Pakistani president under pressure in the first place.
Diplomacy is a delicate business, but you can understand the frustration that surrounds an insurgent supply chain crossing into another country.
There is also the problem of those accused of human rights abuses still holding positions of power. In the delicate position Afghanistan is in, President Karzai is much safer having potential enemies on his side, and giving them positions of power is the most successful way to do that.
It's not good in the long term and it erodes popular support for the government, but many feel it's too early for any kind of truth and reconciliation process - that the country is simply not stable enough as yet.
Afghans have equally strong views about the Western lifestyle, should they send their armies to change the Western lifestyle?
Mateen Mirza, Bahrain
The West has ulterior motives for sure - preventing Afghanistan again becoming a haven for terrorism - but it knows the only way to do that is to help the country develop.
Perhaps President Karzai is not the answer - perhaps a different form of government is, but the country needs the space and time to do that itself.
That is why the Western forces are here and they are supported as Afghans know the alternative is a return to civil war.
There are always questions over whether the West is trying impose its own cultural order on places such as Afghanistan and that is a serious worry, but the Afghan people have never liked foreigners and have never bowed to them, so why should they start now?