Its revealing looking at a map of Ukraine and the extent of Russian advances in the south, which seem to be bounded to some extent by natural barriers (large rivers etc). Kherson is not that far from Mikolaiv, which remains in Ukrainian hands - I wouldn't be surprised if there's a push to retake it sometime soon. Also, Mariupol is only a few tens of kilometres from the Russian border - amazing its been able to hold out for this long.