The UN report on the widespread use of torture by the Afghan intelligence agency and police force is not just an indictment of Nato-backed security forces. It also represents a giant question mark over the workability of the west's strategy in Afghanistan.

Afghan prisoners look out through a window at Kabul prison. (Photograph: Silvia Izquierdo/AP) That strategy involves containment of the insurgency until the end of the 2014, when the US, Britain and their allies are to withdraw combat troops. Meanwhile, the plan is to build up and improve the Afghan government and its security forces, while exploring the possibility of a political settlement.

The trouble is that each element of the plan has an impact on the others, and not necessarily in a good way. The routine use of torture by the intelligence service (NDS) and the police is part of a wider picture of excess and abuse of the Afghan population that is fuelling the insurgency. Most senior Nato officers and western officials now acknowledge that the venality of the government system is a bigger driver that any popular ideological alignment with the Taliban and its allies.

Furthermore, if this is how the security forces treat the Afghan people, then building them up – from 305,000 this year to 350,000 by 2012 to 400,000 by 2013 – could make the problem worse rather than better. The army generally has a better reputation, as does the small Afghan National Civil Order Police, Ancop, but NDS and the general police force are big and ubiquitous enough to poison the well when it comes to popular support for the government.

Compounding this threat is an ethnic dimension. Despite strenuous efforts to recruit in the south, only 3% of the recruits at the national military training academy in Kabul are southern Pashtuns. If this is not improved and no progress is made towards a political settlement in the next two years, then all the effort and resources ploughed into the Afghan security forces could end up providing the skills and equipment for a bigger, more bloody, civil war.

These fears are real and growing in western capitals. A UK review of progress in the Afghan conflict, due to be completed in mid-November will talk about the "significant risks" of civil war or a "Talibanisation" of the Pashtun belt and the further destabilisation of Pakistan. The former Isaf commander General Stanley McChrystal said last week that the force was only "50% of the way" to meeting its goals because "we didn't know enough and we still don't know enough" about the country in which they are fighting. Time is running short to cover the remaining 50%, especially if Nato's central ally, the Kabul government, is going in the wrong direction.