The central role of the foreign forces deployed in Afghanistan is to train the national army and police to a level so they can maintain order in the country and counter the threat of the Taliban when Nato withdraws by the end of 2014.
Given the scale of the task and the speed with which it has to be completed, many have always doubted it could be achieved to anything but a mediocre level.
The advent and increasing growth of so-called "Green on Blue" attacks, where Afghans turn their weapons on their foreign mentors, is in danger of making even that mediocre goal seem almost impossible.
The bulk of the training and mentoring is carried out by British and American forces based in Helmand and Kandahar.
These are the two most deadly provinces, where the Taliban are strongest and where the production of opium-providing poppies gives them an unstoppable revenue stream.
The Taliban have claimed responsibility for the latest attack that killed a soldier from 28 Engineer Regiment. That may or may not be true, but they have promised to infiltrate for years and the poppy revenue gives them the ability to pay would-be converts far more than the Afghan government pays its armed forces.
Isaf force commanders have attempted to introduce protocols to protect their people.
On patrol and in remote camps soldiers regularly appoint a colleague, a so-called Guardian Angel, to watch their backs while they work, soldiers always carry loaded weapons, counter-intelligence has been boosted and recruitment procedures have been tightened to better assess who is signing up.
The effect: Relations between Nato personnel and their Afghan colleagues have worsened and the Green on Blue attacks have actually got worse.
Nato commanders and the Afghan government have continued to maintain that these attacks are largely a clash of cultures.
It is claimed Afghan soldiers angered by a perception of Western decadence and lack of respect, or angered at carrying out orders from foreign mentors, "snap" and attack unexpectedly.
Certainly this has happened. I have been on many joint patrols where relations between the two forces have been terrible. But in my experience the British soldiers do almost all the hard work; manually stacking water and food, lighting fires and - oh yes - actually doing all the fighting.
I have witnessed many instances where young British soldiers have slept outside in freezing conditions rather than risk being sexually molested by Afghan soldiers and thereby avoiding an understandable and likely confrontation.
However, there have been some well documented atrocities by American soldiers on civilians and also stories about the desecration of the Koran and the bodies of dead Taliban fighters. Those, and the policy of night raids (now greatly controlled and reduced) on villages that have led to civilian casualties, certainly acted as a recruiting sergeant for the Taliban.
But in reality, having realised they couldn't defeat the Western forces, the Taliban have moulded their war of attrition to suit their strengths. Persuading men to turn against the army, the police and their mentors is certainly part of their plan.
The Taliban know that the war is unpopular in the West. They know that more deaths, when the withdrawal is imminent, seem a pointless waste to much of the population in the coalition countries.
The decision to announce a timetable for the withdrawal, and sticking to it, means the Taliban have no desire to negotiate anything. They can bide their time and undermine the credibility of the whole Afghan project.
When the withdrawal happens the Taliban will strengthen its grip on the south of the country and use its opium revenues to fund a potential civil war with the cities where the government clings to power.
President Karzai travels to the US this week to meet President Obama for talks about future troop levels. He can be certain that the Green on Blue issue will be at the top of the agenda.