(2) History aside, Ukraine is now strongly inclined not toward Russia but toward western and central Europe and their greater freedom, rule of law, democratic accountability, and higher standards of living. Moreover, a decade of aggression and now a general invasion make for great hostility by Ukrainians toward Russia and all things Russian.
(3) Russian tanks are markedly inferior to the US and NATO models of main battle tanks now beginning to flow into Ukraine. Moreover, Russian military organization, training, and doctrine are obsolete, reliant on brute force, rigid plans, numerical superiority, and on Soviet experience in WW II.
In contrast, Ukraine has adopted the US and NATO combined arms approach, which emphasizes speed, flexibility, and the coordination and application of military force from different combat arms toward decisive common objectives. For examples of how that works, review Germany’s invasion of France in 1940 and the US invasion of Saddam’s Iraq in the Gulf War in 1990-91. In both instances, combined arms tactics beat numerically superior forces, with small, fast, and smart beating big, slow, and stupid.
For Ukraine, the best approach to retaking Crimea is to destroy the Kerch bridge and the rail lines and roads that supply Crimea and to cut off the Russian water and electric supply there. The new extended range missiles approve for Ukraine will do that with relative ease. As the Russians try to use their best armor and mechanized units to relieve Crimea, they will be wrecked by a relative handful of Western model main battle tanks, infantry fighting vehicles, and well-directed artillery and missile fire of various types.
As with other autocracies, Russian history provides examples when economic distress and military defeat led to regime change, such as in 1905, 1917, and 1989. For Putin, the greatest risk comes from the oligarchs and from the Russian military and security services. Defeat in Crimea would almost certainly prompt Putin's ouster and collapse the Russian military as an effective combat force.