It is all but impossible to conduct large-scale military operations in built-up areas without incurring civilian casualties. So there is a melancholy inevitability about the news that 12 Afghan villagers have been killed by two stray rockets at the start of Nato’s offensive in southern Afghanistan. This will no doubt cause unease about the progress of what is described as a civilian protection mission. But, unless recklessly repeated, it should not be a decisive factor in determining its success or failure.

Operation Moshtarak is the most ambitious move yet in the US-led strategy of extending security and commercial institutions through Kandahar and Helmand provinces. The objective is to give ordinary Afghans and insurgents the choice of not siding with the Taliban. Its success is important to breathe fresh energy into a flagging Afghan mission. The military operations have gone to plan. Attempts to suppress civilian casualties by giving prior warning of the operation do not appear to have compromised it. Yet success will not be determined on the battlefield.

The challenge for Nato is not to take ground, but to hold it. If it can do so, the casualties incurred in the operation – both civilian and military – should be bearable. But if it cannot, even after the much proclaimed surge, already wobbly political support for the war may deteriorate further.

There are two big worries in this regard. The first is that there are still insufficient boots on the ground to do the job. Compared to the forces Nato deployed in the former Yugoslavia, for instance, the post-surge force in Afghanistan is very thinly stretched. Peace and security were restored in Bosnia with a ratio of one soldier for every 50 citizens. The coalition is operating only with a ratio of about 1:200. That is high given the task it has set itself.

A second concern revolves around the post-combat stage. For day-to-day security, Nato will rely on Afghan forces. Commanders’ claims that training is curing the police of its venality and corruption are met with open scepticism. Meanwhile the army is ethnically dominated by Tajiks and Uzbeks. This is not a recipe for happy community relations in Pashtun-dominated Marjah.

The success of this offensive is not the only challenge facing Nato. It has also to deal with the perceived illegitimacy of the Karzai government and to find a way of talking to the Taliban that does not involve scuttling. But success in Helmand is a necessary first step towards these objectives.

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