A disciplined Afghan army and police force are the government’s best hopes of holding power against the Taliban and are the core of Nato’s strategy. But effective training faces obstacles in corruption, illiteracy, disappearing supplies, low morale and discipline – and, crucially, the difficulty of creating an effective force made from hostile ethnic groups. These same police and army face a growing insurgency, whose grit could be seen in last weekend's Nuristan battle. Hundreds of militants stormed an outpost, killed eight American troops and captured 20 Afghan police and soldiers. General Stanley McChrystal's controversial plan to double the number of Afghan security forces hinges on the success of US and UK units in Lashkar Gah, struggling to instil discipline in local police reserves. But, if current observations by reporters are accurate, they are struggling to build infrastructure that will let them leave the region in Afghan hands. The disarray of training sites like Lashkar Gah is not a good omen for that self-sufficiency. Is there an echo of Vietnam here?