Russian troops gained terrain in eastern Ukraine, depriving Ukrainian units of their main supply route to the city of Avdiivka, which has been the site of fierce battles since October as Moscow seeks to claim victory there ahead of next month’s elections. “Supplies to Avdiivka and evacuation from the city are more difficult, but a timely prepared logistical artery is now being used,” Dmytro Lykhoviy, the spokesman in charge of the front line section, said on Ukrainian television on Thursday. Overall, the front line is moving strongly and some Ukrainian units have had to retreat to “more favour…