At an industrial estate near Kyiv, a group of engineers stand next to a tube. The metal device is part of a homemade rocket. After twiddling with an ignition cable, the engine sparks into flame. There is a terrifying, ear-splitting roar. Two dogs that guard the compound slink away and hide; swallows fly off. The centre of the pipe glows red. After a minute, the awful din stops. Welcome to the Trembita, also known as the “people’s missile”. The prototype is Ukraine’s 21st-century answer to the V-1 flying bomb, or doodlebug, the long-range ballistic missile used by Nazi Germany during...