There is obviously a huge risk in sending an extra 40,000 machine-gun wielding troops into a country they don't understand to "clear" huge areas of insurgent fighters who look exactly like the civilian population, and establish "control" of places that have never been controlled by a central government at any point in their history.

US aerial attacks on the Afghan-Pakistan border have killed 14 al-Qa'ida leaders, at the expense of more than 700 civilian lives. He says: "That's a hit rate of 2 per cent on 98 per cent collateral. It's not moral." It explains the apparent paradox that broke the US in Vietnam: the more "bad guys" you kill, the more you have to kill.