Explainer: Mariupol, the ruined port city that Russia says it has 'liberated'

The port city of Mariupol on the Sea of Azov, reduced to a wasteland littered with bodies by nearly two months of siege and bombardment that Ukraine says killed tens of thousands of civilians, is a big strategic prize for Russia.

President Vladimir Putin on Thursday declared the city "liberated" after nearly two months of siege, despite leaving hundreds of defenders still holed up inside the giant Azovstal steelworks.