The "Western troops can't operate at that altitude" criticism heard about Western troops fighting in Afghanistan is nonsense. While the thinner air at higher altitudes does slow most people down a bit, it is a minor thing for men in good physical condition. Ask anyone who goes in for Winter (or Summer) sports at Rocky mountain resorts. While the hotels post signs to be careful because of the altitude, this is aimed mostly at people who are not in good physical shape. US and British troops are in great physical shape. Their only problem is that they hump a lot of gear, but most of it is body armor and weapons, which is why the casualties tend to be so lopsided. The Afghans don't carry all that equipment because they don't have it (although most Afghans will gladly wear a flak jacket if they can get one) and because most of them operate from local villages or camps. The military has long experience training and fighting at high altitudes. They know what the impact will be and, at least in the American and British forces, are ready for that sort of thing.