What’s happened here is the the Ukrainians have been pilfering gas from the transit-pipes for years and the Russians have been looking the other way (for whatever reason). Finally, at the end of last year, the Russians got fed up and told Ukraine that they can damn well pay for the gas, same as anyone else. In response, the Ukraine shut off the transit-pipes in hopes to blackmail Russian companies into giving them significantly lower prices on the gas than other European customers are paying.
Once the north-stream pipeline is completed (which will run under the baltic sea directly to Germany) and the expansion of the blue-stream Russia-Turkey pipeline under the Black Sea is upgraded, Ukraine won’t have any leverage anymore.
Truth is, Russia needs the gas to flow as much as, or more, than Europe does. It’s one of their major sources of foreign trade and currency. Every second that gas is turned off is a second Europe is working on alternatives and Russia can ill afford that. While I distrust Russia in every instance, in this particular it’s the Ukrainians doing the mugging.
Oligarchs. IE - Mob Bosses.