In this harsh and unforgiving part of southern Afghanistan, where thousands of US Marines are battling the Taliban this summer, the growing prevalence of roadside bombs means that even a small mishap can have deadly consequences.

Made primarily of large quantities of homemade explosives, the bombs have killed at least a third of the 16 Marines who have died in Helmand since they launched their offensive in early July. The ever-present threat has made the US push in the southern Helmand River valley tougher than US commanders initially anticipated; Marines have seized vital crossroads and population centres, only to discover that Taliban insurgents had filled in the dirt roads behind and around them with bombs.