Troops’ use of patches bearing Nazi emblems risks fueling Russian propaganda and spreading imagery that the West has spent a half-century trying to eliminate. Since Russia began its invasion of Ukraine last year, the Ukrainian government and NATO allies have posted, then quietly deleted, three seemingly innocuous photographs from their social media feeds: a soldier standing in a group, another resting in a trench and an emergency worker posing in front of a truck. In each photograph, Ukrainians in uniform wore patches featuring symbols that were made notorious by Nazi Germany and have since become part of the iconography of...