En Poy was minding cattle in a former Khmer Rouge stronghold in Cambodia when he set off his first landmine. The blast from the rusty relic he picked up cost him an arm and an eye. It also inspired his career with non-profit organisation Cambodian Self Help Demining, which clears landmines and unexploded ordnance across the country, deadly remnants of wars from the last century. Groups like Poy’s that rely on foreign aid are struggling as donors shift funding for humanitarian demining towards...