The five-month wait before US Congress approved $61 billion in military aid to Ukraine may have caused lasting damage that will be felt on the frontlines for months to come. Russian forces have used the “artillery drought” hampering Ukraine’s defenses since December to push forward on the eastern front near Avdiivka, making the largest advance since the early months of the war. Moscow’s progress has prompted warnings from senior Ukrainian military officials of a possible threat to Kyiv’s supply lines and hubs in the east, which are now perilously close to being in range of superior Russian firepower. The bleak...