Julius Cavendish: Struggle to destroy the bombers in the fields of Kandahar

Villagers are threatened with beheading if they inform on the Taliban

The four men digging on the road exploded silently. The video feed from a US helicopter gunship showed a volley of rockets dispatching them with brutal efficiency. Under the cover of darkness they had been planting an improvised explosive device (IED) on a route used recently by American soldiers.

It was a rare success in the battle against the Taliban bomb-makers, responsible for so many coalition casualties in Afghanistan. They were, perhaps, the kind of men that may eventually, if the peace plan approved in London actually works, accept Western money to come off the battlefield and turn instead to working on a farm or be trained for a job.

For now, the emphasis of the Nato campaign remains firmly fixed on preventing civilian casualties. The problem is that insurgents laying IEDs are usually long gone before soldiers get confirmation of all the criteria needed to order an attack.

Instead, the foreign troops focus on trying to persuade villagers that home-made bombs are just as much a threat to farmers in their fields as they are to Nato patrols and that informing on the insurgents is the only solution. "We need your help," Lieutenant Mark Morrison, a US platoon leader deployed in southern Afghanistan, told a group of Afghan farmers on a patrol. "I know how to kill the Taliban – we are very, very good at that. What I need your help with is finding where they come from and where they go to. You need to tell me who doesn't belong with you."

It was a message he repeated to anyone he stopped to talk to.

Making a common cause with the civilians whose support is so crucial to the counter-insurgency campaign seems a sensible ploy. Only by squeezing the Taliban out of the civilian populations they hide among will Nato force them to the negotiating table, as the US General David Petraeus outlined this week.

But persuading Afghans whose only priority is survival to take a stand is also time-consuming and relentlessly frustrating. Although several civilians had been killed by IEDs in Lt Morrison's operations area in Zhari, a volatile district in Kandahar province, few seem ready to provoke the insurgents. Occasionally someone does oblige; most profess ignorance of the insurgents' doings or blatantly lie. Which is not surprising considering the punishment they risk.

Using night letters tacked to village mosques, the insurgents threaten to behead anyone who talks to the foreign soldiers and they have spies in each village keeping vigil. Labourers in the fields want neither to be seen talking to Nato patrols alone nor be questioned in a group when one of its number may be a Taliban informant. "I have no problem with you guys," a villager said. "But we are scared of the bad guys. They kill innocent people if they see them giving information."

For soldiers engaged in gun battles with the insurgents on an almost daily basis this equivocation is exasperating. "The sad thing is, I think the only people in this country with any courage are the fucking Taliban," Lt Morrison said after yet another fruitless conversation.