North and South Korea are still technically at war, seventy years after the Korean war officially ended. A two-and-a-half-mile wide buffer zone, the DMZ separates the two countries. It's a no-go area for humans, which has made it a rare haven for wildlife. Elizabeth Palmer visits the DMZ with South Korean biologist Seung Kim to scout for animals and hear how lasting peace – while good for people – is a looming threat to nature