The US does not have the power, as we have now seen over the last nearly 3 years. We have the power to compel Ukraine to do our bidding, even to the detriment of Ukraine, but it was and is politically untenable for the US to go to war with Russia over Ukraine.

I would bet a LOT that Russia will NOT take all of Ukraine. Western Ukraine is not ethnically Russian like Eastern and parts of Central Ukraine are.

If you haven't noticed, there is NOT an insurgency in either Crimea (annexed 2014) or the parts of Luhansk and Donetsk that Russia took over nearly 3 years ago. The vast majority of the population is not anti-Russian to the point of armed resistance.

That would NOT be the case in very anti-Russian Western Ukraine, and Russia knows that. At most I see Russia taking parts of Central and Western Ukraine as bargaining chips, as Ukraine tried to do with Kursk.

Why do you think the US (and Europe) need Ukraine?