On a freezing gun range in western Denmark, rows of blonde ponytails poke out of camouflaged helmets, as pale blue eyes lock on moving targets. A platoon of young military recruits is learning how to fire in the field. As Denmark finds itself threatened on two fronts, the country is turning to an unexpected new weapon — teenage girls — to help defend the kingdom. Among the new troops is Mary Petersen, barely five-foot tall, who nails her shots with the precision of a seasoned soldier. "I personally enjoy the shooting a lot," she tells Foreign Correspondent, shrugging off the...