Russia is losing men and equipment at an enormous rate, and all they have to show for it is a tiny bit of front line movement in some areas as Ukraine slowly falls back to avoid sacrificing lives needlessly.

The most effective move Russia has is terror bombing Ukrainian civilians with long range weapons. And that's expensive. Probably millions of dollars per Ukrainian killed.

Meanwhile, Ukraine can do the exact same thing, and more effectively as more of Russians economy is based on oil and gas exports. Highly vulnerable infrastructure that burns intensely when hit.

Russia's main defense is political: putting pressure on Ukraine to not hit Russian targets in the name of "peace negotiations".