ARMED to the teeth and hurtling through Greenland’s icebound vastness by dog sled, they are the elite special forces accustomed to fighting off savage polar bears. Now the Sirius Dog Sled Patrol could be pitched against US forces if Donald Trump goes ahead with his threats to invade this mineral-rich Arctic wilderness. The specialist Danish naval unit would be daunting adversaries. Braving hunger and frostbite — in a world where one mistake can be fatal — they have become masters of their environment. For up to five months at a time, they conduct long-range reconnaissance missions through this harsh land...