The last time that Ursula von der Leyen travelled to Kyiv, in late February, she arrived in the midst of a gruelling winter. Ukraine was suffering widespread blackouts caused by Russian strikes. The population endured sub-zero temperatures without heating. This week, on her second trip this year, she declared upon arriving at the train station: “The tide is turning.” It was a bold statement that captured a remarkable transformation in less than five months. With the battle lines stuck in a war of attrition, Ukraine has moved the fighting to the skies, launching long-range drone strikes against Russia’s oil refineries,…