Forty miles from the northeastern front line of Russia’s war against Ukraine, Olena and her nephew Boris keep a watchful eye on their children and grandchildren as they play in a sun-splashed park of this small city. “Our moods are tense. Every day we worry about what might come down on us from the sky,” says Olena. “But the children have to be able to get out and have fun.” The aunt and nephew – who chat with a foreigner on condition of withholding their full names – concur that it was a morale boost to their industrial town when Ukrainian forces in December and January forced Russian troops to retreat from the nearby city of Kupiansk. Why We Wrote This Russia is no longer making noteworthy battlefield gains. If anything, it’s been Ukraine, aided by its technological prowess, taking back small pieces of territory. After a punishing winter, Ukraine is in a surprisingly encouraging place.…