Abdullahi Yusuf was just 3 years old the last time he’d been on an airplane. But when he walked into the Minneapolis–St. Paul airport 15 years later, he tried to look like he’d been traveling all his life. He wore brand-new khakis and a pink oxford shirt — casual travelwear, he thought. He’d considered packing painkillers and antibiotics in case they didn’t have medicine where he was going but abandoned the idea for fear it would arouse suspicion at security. He was struggling to keep his emotions in check. “It was my last day with my family,” he said. “My last day in America. The last day of life as I knew it.” Although Yusuf had turned 18 earlier that spring, his morning ritual still included his dad driving him to school. The ride that particular May morning had been excruciating — how could he make small talk? When they finally pulled up to the school, he suddenly threw his arms around his father’s neck and held him. “He thought that was strange,” Yusuf said. “But I thought it was my last time seeing my dad. I wanted a good memory.” Hours later, Yusuf had made it through security. Someone helped…