Smolensk and Vitebsk were key railway junctures leading to Minsk. Additionally, there was Bobruisk in the south, with railways running towards Kiev nearby.
However, the issue was that Kiev was already a primary offensive target for the German Army Group in the south, making it nearly impossible for them to support Minsk.
Should Vitebsk and Smolensk, which could potentially support Minsk, become blockaded by the German Army, the Russian supplies and reinforcements would no longer be able to reach Minsk.
The newly appointed Commander-in-Chief of the Russian Western Front Army, Timoshenko, certainly saw through the Germans' intentions. But the problem was, having only been in command for a few days, the Western Front Army had not replenished its troops and equipment.