Ukraine launched one of its largest drone offensives of the war overnight into June 6, sending more than 400 unmanned aircraft deep into Russian territory and striking targets that included a naval weapons depot near Saint Petersburg, an oil refinery in Siberia, a port in Russian-occupied Mariupol, and munitions warehouses in the Leningrad region. Russia’s Defense Ministry claimed its air defenses shot down 376 of the incoming drones, a figure that, if accurate, still left dozens reaching their intended targets across a geographic spread stretching from the Baltic coast to western Siberia. The attacks came on the final day of...