Andriy watched anxiously as Russian soldiers connected his mobile to their computer, trying to restore some files. Andriy, a 28-year-old marketing officer, was attempting to leave Mariupol. He had deleted everything he thought a Russian soldier could use against him, such as text messages discussing Russia's invasion of Ukraine or photos of the devastation in his city caused by weeks of relentless shelling. But the internet in Mariupol, a once bustling port in southern Ukraine, had been cut off as part of the siege imposed by Russia, and Andriy had not been able to take down some of his social...