Poison, exploding cigars and shooting down planes: tales of espionage and statesmanship. Government-ordered assassinations may seem the stuff of spy novels and movie scripts, but they seem to have entered the realm of reality of late. Why do states choose to take this action and can we measure their success? Edward Stourton assesses how various governments -including Israel, Russia, America and the UK - have dabbled in assassination and asks whether it works as a tool of foreign policy. Producer: Phoebe Keane