Maybe it's because I am very PO centric in my thinking, but I believe Gas is more of a factor in the conflict than is generally being assumed.
I understand about 80% of EU's gas imports from Russia come via the Ukraine and there have been major problems in the past with mis-appropriations of gas intended for EU by Ukraine. Don't know what the impact would be if Russian gas was stopped, as there are limited transport issues, think it would be mainly heating, but am unsure of dependence on gas for electrical power generation.
http://en.wikipedia.org/wiki/Russia%E2%80%93Ukraine_gas_disputes