A river frozen deeply enough to hold truck/tank traffic can be, if it has a smooth surface, a boon to military transport. A river frozen too deeply for normal boat traffic, but not deeply enough to hold truck/tank traffic, or with a jagged surface from cycles of freezing and thawing, can be a significant barrier to military transport.
Oh, there ya go. Talking sense. Stop…the Putinistas won’t like that. Lol.