KYIV, Ukraine—Valeria Sydorova walked toward the Russian border post, her nerves steeled by the proximity of her goal: to get home. The 17-year-old had wiped her phone of anything the Russians might find suspicious, had traveled solo for hundreds of miles and was now within touching distance of Ukraine.
Russian border guards, shocked to see a teenager on her own, quizzed her: “Where are your parents? What do you mean you are alone?”