Trenches are not new to Ukraine. Trench warfare has long been a feature of the battle in eastern Ukraine for the Donbas region. Ukrainians fight from their own trenches on their side of the line near Popasna, where Russians are waging an intense campaign to dislodge Ukrainian troops from the city of Bakhmut. But the pace and the scale of Russian construction over the last couple of months is unmatched. All of the structures in the image above appeared within six days. The fortifications show how Russia’s military is trying to set up more robust, defensible positions against Ukrainian pressure,...