Accused of wasting huge sums on failed projects in Afghanistan, USAid has adopted a new strategy to undermine the Taliban by spending up to $500m a year to help farmers, primarily in the heartland of the insurgency.

William Frej, who in May took over in Kabul as head of the US development agency, has pledged to increase rapidly the scope of schemes to provide irrigation, seeds and tools to villages torn between backing the Afghan government and the strengthening insurgency.