[beardyw]

It is not impossible. Russia is adamant that Ukraine should not join NATO, and you can understand why. Positive moves from the US in that direction would have the outcome we see.

To what extent NATO members wish (or wished) to defend Ukraine will become evident, but their inaction today does not bode well.

[Edit] Guardian headline now: "Germany shelves Russian gas pipeline after Putin orders troops over border"

[thevagrant]

I'd go with a more simple explanation. Russia decided to invade, because they chose to do so. It's no one else's fault.