Russia is saying the defenders of Mariupol have until Sunday to surrender if they want to be treated as POWs according to the Geneva convention (not that they've been following it much anyway.). They didn't say what would happen if they failed to do so, but, yeah, the implication is there
https://www.bbc.com/news/live/world-...ost_type=share
Sounds like the Russians know they can't take the steelworks without catastrophic losses and are trying to scare the defenders into surrender.
You just have to look at the trouble the industrial complex on Stalingrad caused the Germans. They never could take the tractor works despite throwing everything at it.