More than 1,000 Ukrainian marines have surrendered in the besieged port of Mariupol, Russia’s defense ministry said on Wednesday of Moscow’s main target in the eastern Donbas region which it has yet to bring under its control. If the Russians take the Azovstal industrial district, where the marines have been holed up, they would be in full control of Mariupol, Ukraine’s main Sea of Azov port, which would allow Russia to reinforce a land corridor between separatist-held eastern areas and the Crimea region that it seized and annexed in 2014.