We can assume that the Russians have considered several military options. First, they gathered this massive amount of force around the city of Drohobych, posing a direct threat to our major city of Kharkiv.
Second, there is this vulnerable direction towards the city of Mariupol, along the Azov Sea. The Russians have been dreaming for quite a long time of creating a land bridge from the Russian mainland to occupied Crimea.
Finally, there are plenty of options with the expansion of the occupation zone into wider Donbass. There can be a lot of possible reasons the Russians want to try to do that, and we can explore it further, but one way or another, they are testing our reactions. They have been testing the reactions of the west, and I think they have badly miscalculated the response.