Kim Sengupta reports from Nanyuki, Kenya.
The man carrying out the dry run is Brigadier James Cowan, who first came to prominence when leading his regiment, the Black Watch, in Iraq's "Triangle of Death" four years ago. In a few months' time, he will be involved in a new chapter in the "war on terror" as British commander in Helmand in what is expected to be a particularly turbulent time.
There is a resonance to this. Iraq was then the all-consuming focus of American and British foreign policy with Afghanistan filed away as a relatively easy victory. But as the allies moved on to dethrone Saddam Hussein, the Taliban returned to a security vacuum to launch the real war.