AP Photo

David Cameron has picked a fine time to make his Afghan debut. Convoy torched; helicopter shot down; the two security advisers to President Karzai whom the West most trusts resigned; and 29 Nato and British servicemen killed in nine days.

The photograph in Thursday’s Times of a burnt-out convoy of Nato supply trucks bound for Afghanistan took me back: not to Afghanistan, but to an earlier visit and another place.

More than 12 years ago I stood at the head of the Asherum Pass in the baking heat of the low, dry mountains of northern Eritrea. “The bodies — thousands of them —”, I wrote in The Times, “have been taken away, but the Russian tanks are still scattered across the valley like children’s ...