BTW, important that Sevastopol is not random choice, but it is strategical point to control Crimea. Control Crimea and coast of azov sea is important, because

BTW, important that Sevastopol is not random choice, but it is strategical point to control Crimea. Control Crimea and coast of azov sea is important, because Russia have powerful internal water routes via azov sea. For example, when Russian black sea warship need some deep maintenance, they use rivers network to reach service facilities in deep country. It is luck for Ukraine, that we have huge part of azov sea coasts, with Mariupol, one of largest steel enterprise of the world and also big port (sure, I mean we control them before war). For Russians, Mariupol was hidden threat, they constantly fear that Ukraine will use power to block Russians from enter sea from Don.