[TigerLikesRoosterNew]

Ukrainian force is small and Russians have vast supply of shells, providing they can successfully delivered to front lines which may be a challenge.

Ukraine will eventually run out of soldiers to fight and all their cities are flattened. That could be what Russia is counting on. But Russian's supply-lines can be cut for extended period, then even the effectiveness of this strategy may be in doubt.

[NorseViking]

How small the Ukrainian military is? It heavily outnumbers the committed Russian forces.