Russia will move eight warships, including three Karakurt class corvettes capable of launching Kalibr cruise missiles, to the Azov Sea, the U.K. Defense Ministry reported on July 7.
“In the context of the war, it also offers an alternative military resupply option should Russia’s over-land routes to southern Ukraine be disrupted.”
If Ukraine cuts the land bridge, I would guess that it’s going to be hard to resupply Russian forces west of the cut via ship, as ships traversing the Sea of Azov will have to pass within range of land-based anti-ship missiles, Neptunes and Harpoons, that could be placed in Ukrainian-controlled territory. Those have a range of about 200 km. The Sea of Azov is about 120 km north-to-south.
My guess is that those systems are not that quick to set up, and easy to target. I know nothing about military, it’s just an uneducated guess.
They both have vehicle-based launchers.
https://en.wikipedia.org/wiki/R-360_Neptune
Look in the gallery section – it shows the launcher.
U.S. Sending Vehicle-Mounted Harpoon Launchers for Ukraine Coastal Defense