Robot infantry get ready for the battlefield

"Please put down your weapon. You have 20 seconds to comply." So said the armed robot in Paul Verhoeven's 1987 movie RoboCop. The suspect drops his weapon but a fault in the robot's software means it opens fire anyway. Nearly two decades later, such fictional weapon-toting robots are looking startlingly close to reality – and New Scientist has discovered that some may eventually help to decide who is friend and who is foe.