A half-dozen U.S. ballistic missiles, fired by Ukraine, slammed into an ammunition depot some 75 miles across the Russian border early Tuesday, setting off further detonations that turned the sky red. The following morning, 10 British-provided cruise missiles pounded the vicinity of a Kremlin-run sanatorium that was apparently used as a military headquarters, smashing one after another in the town of Marino, located in Russia’s Kursk region about 20 miles from the front line there. These two strikes, the first Kyiv launched with Western-supplied missiles after receiving authorization from the U.S. and allies, show the range of military targets now...