Staff at Ukraine’s largest steelmaker, Metinvest, watched in horror last February as their security cameras showed invading Russian forces closing in on their factory. But a lack of defences for their own industrial plants prompted an idea that has since taken on its own momentum: creating a Potemkin army. Metinvest’s hope is that the fake weaponry it now makes for the Ukrainian armed forces – tapping into a long military tradition of decoys – is luring Russia into wasting expensive resources destroying it. As Russia invaded, “we dug trenches with our equipment and built fortifications around the plant. But we...