The question now may not be the historic incompetence of the Russian military, but whether ANY determined nation (even a 3rd worlder) can resist missiles and boots on the ground. Parallels of our own military exist (in Korea, Vietnam, Iraq, Afghanistan) where bombs and aircraft weren't enough, ground troops may have been decimated if we pushed too far (I'm assuming also that the Nazis were an exception for both US and Russia who resoundingly won due to Nazi overreach and collapse). This goes back to Carthage-Rome where Hannibal's "artillery" (elephants) were invincible until the Romans learned guerilla warfare, Hannibal's overreach was exposed to the point of successful sacking of Carthage. The "softening" of the enemy via bombs didn't work during the Blitz nor at Iwo Jima. Even my father's WW II B24 cohorts used to joke "The Germans seem to fly pretty well without ball bearings" (translation: the bombing was relatively ineffective).